Map Check Errors

Document Summary: Descriptions of possible map check errors.

Document Changelog: Created by Amitt Mahajan^?.

Errors

negative or zero distance to [Navigation Point]!

This error is caused when there is a navigation point with negative or zero distance to another navigation point. This can be problematic because this case should be impossible to achieve and is usually the result of a path building error. This error can be resolved by rebuilding paths.

Cannot reach [Navigation Point] from this node!

This error is caused when there is a NavigationPoint with bMustBeReachable set to TRUE that is unreachable from some other node. This is usually the result of placing the node in a location that cannot be reached by the AI and can be solved by either setting the bMustBeReachable flag to FALSE or moving the navigation point to a location that is reachable by all other navigation points.

This type of NavigationPoint cannot be based on [Actor]

This error is caused when there is a NavigationPoint on a base that it is not compatible with. This is usually the result of placing a normal navigation point on a non-static base. This error can be fixed by placing the navigation point over a static base and using a specialized navigation point for dynamic bases (such as a LiftCenter for lifts).

Only XX PlayerStarts in this level (need at least YY)

This error is caused when there is a required amount of player starts and the map contains less than the required amount. This will keep the map from being playable. To solve this problem, add more player starts to the level or reduce the required amount of player starts by modifying the default value of MinNumPlayerStarts for the Scout class used by your game.

Navigation point not on valid base, or too close to steep slope

This error is caused when there is a path node that is not on a floor or is near a wall or other steep slope. This is a problem because actors will be unable to properly travel to the node's location. This error can be fixed by moving the navigation point to a valid location.

PlayerStart is not useable

This error is caused when a PlayerStart actor is in a invalid location. This is a problem because the spawning code cannot safely place a player actor there without falling off the world or placing the player into a obstacle. This error can be fixed by moving the player start to a valid location.

No LiftExits associated with this LiftCenter

This error is caused when there is a LiftCenter actor without a corresponding LiftExit. LiftCenter actor's are used to help AI pawns navigate lifts properly by telling them where a safe place to stand on the lift is. LiftExit's help identify where the AI pawn should exit a lift. Having a LiftCenter without a corresponding LiftExit keeps the AI from knowing how to properly exit a lift. This error can be fixed by adding a LiftExit actor if one doesn't already exist and then associating it with the LiftCenter actor by going to the LiftExit actor's Property Window->Lift Exit Category and setting the MyLiftCenter to be the LiftCenter actor.

No LiftCenter associated with this LiftExit

This error is caused when there is a LiftExit actor without a corresponding LiftCenter. LiftCenter actor's are used to help AI pawns navigate lifts properly by telling them where a safe place to stand on the lift is. LiftExit's help identify where the AI pawn should exit a lift. Having a LiftCenter without a corresponding LiftExit keeps the AI from knowing how to properly exit a lift. This error can be fixed by adding a LiftCenter actor if one doesn't already exist and then associating it with the LiftExit actor by going to the LiftExit actor's Property Window->Lift Exit Category and setting the MyLiftCenter to be the LiftCenter actor.

Extra Cost cannot be less than zero!

This error is caused when there is a NavigationPoint derived actor with a Extra Cost property that is less than zero. This can be problematic because Extra Cost is used to make a path less likely to be taken by the AI, but when it is less than zero it can cause problems in the navigation tree since it makes a path more likely to be taken. This error can be fixed by going to the actor's Property Window->Navigation Point Category and setting Extra Cost to a value that is greater than or equal to zero.

Failed to add PortalMarker!

This error is caused when a PortalTeleporter actor is unable to create a portal marker for AI path finding. A portal marker is used to figure out the location of an actor after they have teleported and have fallen to the ground. This error is usually the result of being unable to place a portal marker on a floor directly below the teleporter and can be resolved by moving the teleporter to a spot where there is a valid floor or creating a floor under the teleporter.

DoorMarker with no door

This error is caused when there is a DoorMarker without a corresponding door. DoorMarker's are used by AI pawns to properly path find their way through doors. This error is the result of creating a door marker without assigning a door to it and can be resolved by going to the DoorMarker actor's Property Window->DoorMarker Category and setting 'MyDoor' property.

#Terrain

Terrain

Improperly Indexed NormalMapLayer Overrides

This error is caused when the NormalMapLayer property points to a non-existent Layer.

Missing Shader Maps

This error is caused when the shader compilation fails due to complexity (too many instructions). Try recompiling the materials via the RM button on the Terrain Editor dialog.

Too Many Textures

This error is caused when the material combinations on terrain components results in too many samplers being used. Simplify underlying materials or remove a layer.

Warnings

[Actor]::[Actor] : Ambient sound has NULL SoundNodeInstance

This warning is caused when there is a AmbientSound actor with a NULL SoundNodeInstance component. SoundNodeInstance is needed in order for ambient sounds to correctly play. This warning can be resolved by deleting the actor and recreating it.

[Actor]::[Actor] : AmbientSoundNonLoop has a non-USoundNodeAmbientNonLoop SoundNodeInstance

This warning is caused when there is a AmbientSoundNonLoop with a SoundNodeInstance of an incorrect type. This is a bug that exists in older maps and can be fixed by deleting the AmbientSoundNonLoop actor and recreating it.

[Actor]::[Actor] : AmbientSoundNonLoop has no Slots containing a Wave

This warning is caused when there is a AmbientSoundNonLoop without any "Slots" that contain a valid Wave asset. Waves are the actual sound data used to play the ambient sound and are required in order for the AmbientSoundNonLoop to function properly. This warning can be resolved by first selecting a Sound Wave asset in the generic browser and then going to the actor's Property Window->AmbientSoundSimple Category->AmbientProperties->SoundSlots and adding atleast 1 soundslot with a non-None "Wave".

[Actor]::[Actor] : Ambient sound has NULL AmbientProperties

This warning is caused when there is a AmbientSound actor with a NULL AmbientProperties component. AmbientProperties is needed in order for ambient sounds to correctly play. This warning can be resolved by deleting the actor and recreating it.

[Actor]::[Actor] : Ambient sound's AmbientProperties has a NULL Wave

This warning is caused when there is a AmbientSound actor whose AmbientProperties component has a Wave property set to "None". The Wave property tells the sound system which wave file to loop for the ambient sound. If set to None, the ambient sound will not play properly. This warning can be fixed by choosing a Sound Wave in the Generic Browser and then setting the Wave property for the ambient sound through the actor's property window.

Ladder is not in a LadderVolume

This warning is caused when there is a Ladder actor that is not encompassed by a LadderVolume. This warning can be problematic because AI pawns require ladders to be within ladder volumes in order to properly path up and down them. This warning can be fixed by placing the ladder within a ladder volume.

[Actor] bStatic false, but is bStatic by default - map will fail in netplay

This warning is caused when there is an actor that had its bStatic property set to false even though the default is true. This warning is usually seen in older maps when bStatic used to be modifyable by level designers and can cause problems in network play since certain assumptions are made about actors that default bStatic to true. Since bStatic is no longer modifyable through the editor, this warning can be fixed by deleting the actor and recreating it.

[Actor] bNoDelete false, but is bNoDelete by default - map will fail in netplay

This warning is caused when there is an actor that had its bNoDelete property set to false even though the default is true. This warning is usually seen in older maps when bNoDelete used to be modifyable by level designers and can cause problems in network play since certain assumptions are made about actors that default bNoDelete to true. Since bNoDelete is no longer modifyable through the editor, this warning can be fixed by deleting the actor and recreating it.

No navigation point list. Paths define needed.

This warning is caused when the path data isn't completely built. This can be problematic because AI pathing will not work correctly when the game is run. This warning can be resolved by rebuilding paths.

[Volume] causes damage, but has no damagetype defined.

This warning is caused when there is a volume that is set to cause damage but doesn't have a damage type defined. A damage type is important because it tells the game code how to handle a actor's reaction to taking damage. This can be solved by going to the actor's Property Window->Physics Volume and setting the 'DamageType' property.

[Actor] : Brush has non-coplanar polygons

This warning is caused when there is a brush in the level that has non-coplanar polygons. This is usually caused by using brush editing tools in geometry mode in extreme ways and can cause missing polygons in the level. This warning can be resolved by deleting the brush and recreating it.

No paths from [Actor]

This warning is caused when there is a NavigationPoint that has no paths origininating from it. This can be problematic because it may mean that the point is unreachable or unusable. This problem can be fixed by moving the point to a reachable location if it is needed or by deleting it if it is unneeded.

Ambient sound actor's AudioComponent has a NULL SoundCue property!

This warning is caused when there is a AmbientSound actor with a NULL SoundCue property. This is a problem because the actor won't actually be playing any sounds. This can be fixed by first choosing a sound cue in the generic browser and then going to the actor's Property Window->Audio Category->Audio Component and setting the 'SoundCue' property.

[Brush Actor] : Brush has NULL material reference(s)

This warning is caused when there is a brush that has a face without a material assigned to it. This warning is usually the result of creating a brush when there is no material selected and serves to let the user know that there may be a default texture surface visible in-game. This can be fixed by assigning a material to the brush.

[Brush Actor] : Brush has zero polygons - please delete!

This warning indicates that you have a brush in the level that doesn't have any polygons associated with it. The brush should be deleted as it isn't doing anything useful.

[Static Mesh Actor] : Static mesh actor has NULL StaticMesh property

This warning is caused when there is a static mesh actor in a level with a NULL StaticMesh property. This can be a problem because the actor exists and is using memory, but doesn't have a static mesh to actually draw. This warning is usually the result of creating a StaticMesh actor without first selecting a StaticMesh in the generic browser. This warning can be fixed by first selecting a static mesh in the generic browser and then going to the StaticMesh actor's Property Window->StaticMeshActor Category->StaticMeshComponent->StaticMeshComponent Category to set the 'StaticMesh' Property.

[Actor] : KActor has a StaticMeshComponent whose StaticMesh's BodySetup is NULL

This warning is caused when there is a KAsset actor that has a StaticMeshComponent with a StaticMesh with a NULL BodySetup property. BodySetup is the physics information for a mesh and is needed in order for KAsset's to animate correctly. To fix this warning you can either change the StaticMesh of the StaticMeshComponent to a static mesh that has a BodySetup or you can add BodySetup information to the existing static mesh using the static mesh editor. See: Collision Reference for more info.

[Actor] : SkeletalMeshActor has no PhysicsAsset assigned.

In order for a SkeletalMesh to have an accurate bounding box, it needs to have a PhysicsAsset assigned in its SkeletalMeshComponent. An incorrect or inaccurate bounding box can lead to the mesh vanishing when its origin is not in view, or to poor shadow resolution because the bounding box is too big.

[Actor] : KActor has BlockRigidBody set to FALSE and no joints.

If an Actor is using PHYS_RigidBody but has BlockRigidBody set to FALSE, it will just fall out of the world when woken, as no contacts will be generated. This is ok when there is a joint to the Actor in question, but probably indicates an error otherwise.

[Actor] : both of RB_ConstraintActor's ConstraintActors are NULL

This warning is caused when there is a RB_ConstraintActor with its ConstraintActor1 and ConstraintActor2 properties both set to "None". Constraint actor's need to be attached to atleast one other object in order to function properly. This warning can be fixed by going the actor's property window and assigning either ConstraintActor1 or ConstraintActor2 to a non-static actor.

[Actor] : RB_ConstraintActor actor connects two static actors!

This warning is caused when there is a RB_ConstraintActor with its ConstraintActor1 and ConstraintActor2 properties both assigned to a static object. Constraint actor's need to be attached to atleast 1 dynamic object otherwise they will never move and thus never actually have a chance to function. This warning can be fixed by going tot he actor's property window and assigning either ConstraintActor1 or ConstraintActor2 to a non-static actor.

[Actor] : RB_ConstraintActor actor is connected to a single static actor

This warning is caused when there is a RB_ConstraintActor with either ConstraintActor1 or ConstraintActor2 assigned to a static object and the other property set to "None". Constraint actor's need to be attached to atleast 1 dynamic object otherwise they will never move and thus never actually have a chance to function. This warning can be fixed by going tot he actor's property window and assigning either ConstraintActor1 or ConstraintActor2 to a non-static actor.

[Actor] : KAsset actor has a SkeletalMeshComponent with a NULL skeletal mesh

This warning is caused when there is a KAsset actor that has a SkeletalMeshComponent with a NULL Skeletal Mesh. KAsset actor's require both a skeletal mesh and a physics asset in order to work properly. This problem can be fixed by first selecting a Skeletal Mesh in the generic browser and then by going to the actor's Property Window->KAsset Category->SkeletalMeshComponent->SkeletalMeshComponent Category to set the 'SkeletalMesh' property.

[Actor] : KAsset actor has a SkeletalMeshComponent with a NULL physics asset

This warning is caused when there is a KAsset actor that has a SkeletalMeshComponent with a NULL Physics Asset. KAsset actor's require both a skeletal mesh and a physics asset in order to work properly. This problem can be fixed by first selecting a Physics Asset in the generic browser and then by going to the actor's Property Window->KAsset Category->SkeletalMeshComponent->SkeletalMeshComponent Category to set the 'PhysicsAsset' property.

[Actor] : DynamicSMActor has a StaticMeshComponent with NULL StaticMesh property

This warning is caused when there is a subclass actor that derives from DynamicSMActor in a level that contains a StaticMeshComponent with a NULL StaticMesh property. This can be a problem because the actor exists and is using memory, but doesn't have a static mesh to actually draw. This warning is usually the result of creating a DynamicSMActor actor without first selecting a StaticMesh in the generic browser. This warning can be fixed by first selecting a static mesh in the generic browser and then going to the actor's Property Window->DynamicSMActor Category->StaticMeshComponent->StaticMeshComponent Category to set the 'StaticMesh' Property.

May be too close to other navigation points

This warning is caused when there is a path node that is very close to another path node. This can be a problem because this path node may not be needed since it is so close to another path node and may be needlessly complicating the navigation tree. If this path node is not needed, the problem can be fixed by deleting the path node.

[Light Actor] has same light GUID as [Another Light Actor]

This warning is caused when there is a light actor that has the same unique identifier as another light actor. This problem can occur because of an error in the duplication of a light and should be resolved by deleting one of the light actors and recreating it.

Nav [Path Node] shares GUID with [Another Path Node]

This warning is caused when there is a path node actor that has the same unique identifier as another path node actor. This problem can occur because of an error in the duplication of a path node and should be resolved by deleting one of the path node actors and recreating it.

[Path Node] is unnecessary and should be removed

This warning just lets the user know that a paticular path node isn't necessary and can be safely removed without affecting AI pathfinding. Unnecessary path nodes should be removed because they are taking up memory without actually adding any extra information to the navigation tree. The warning can be removed by deleting the path node.

[Actor] in same location as [Another Actor]

This warning is caused when there is a actor that is in the same exact location as another actor. This warning is usually the result of a accidental duplication or paste operation. It can be fixed by deleting one of the actors, or disregarded if the placement was intentional.

Actor has bAcceptsLights set but is in no lighting channels

This warning is caused when an actor is set to accept lights but doesn't have any lighting channels flagged. This is a problem because the actor expects to be lit but receives no lighting contribution from any sources. The problem can be resolved in 2 ways:

1. If the actor is supposed to accept lighting, go to the actor's property window->Collision Category->Collision Component->Lighting Category->Lighting Channels. Then check the lighting channels that the actor should receive lighting from.
2. If the actor is supposed to be unlit, go to the actor's property window->Collision Category->Collision Component->Lighting Category. Then set the bAcceptsLights checkbox to FALSE.

Actor has bAcceptsLights set but only uses unlit materials

This warning is caused when an actor is set to accept lights but isn't using any materials that actually are affected by lighting. This is a problem because the actor is receiving lighting but none of the materials actually show the effects of lighting because they are set to be unlit. The problem can be resolved in 2 ways:

1. If the actor is supposed to accept lighting, change the materials the actor uses to materials that are affected by lighting.
2. If the actor is supposed to be unlit, go to the actor's property window->Collision Category->Collision Component->Lighting Category. Then set the bAcceptsLights checkbox to FALSE.

[Actor] has invalid DrawScale/ DrawScale3D

This warning is caused when either DrawScale, DrawScale3D X, DrawScale3D Y, or DrawScale 3D Z is equal to zero. Meaning that the actor will not be shown because it is being scaled to zero on one of its axis. To solve this problem, change any DrawScale's that are zero to be non-zero by selecting the actor and changing its drawscale at the bottom of the main UnrealEd window.

[Actor] is set to PHYS_RigidBody but has no CollisionComponent

PHYS_RigidBody requires a valid CollisionComponent such as a StaticMesh or SkeleltaMesh. It is not valid to set PHYS_RigidBody on Actors which only display as sprites for example.

[Actor] is obsolete and must be removed!

This warning is caused when there is an instance of a actor in a level that has been marked deprecated. This is usually because a actor was marked deprecated after the level was created, but the map was never updated. This can be fixed by simply deleting the actor.

[Actor]::[Actor Component] is obsolete and must be removed!

This warning is caused when there is an instance of a actor component in a level that has been marked deprecated. This is usually because a actor's component was marked deprecated after the level was created, but the map was never updated. This can be fixed by simply deleting the actor and recreating it.

[Actor] : InterpActor's StaticMeshComponent has BlockRigidBody, but is based on an actor with PHYS_RigidBody

This warning is caused when there is an actor with the Physics property set to PHYS_RigidBody while its StaticMeshComponent has BlockRigidBody set. This can cause a problem because it will create a feedback loop within the physics system where the StaticMeshComponent will push the actor which in turn will push the StaticMeshComponent and so on. This can be fixed by either changing the Actor's Physics to something other than PHYS_RigidBody or changing the StaticMeshComponent of the actor to have BlockRigidBody set to false.

Paths need to be rebuilt!

This warning is caused when paths or path nodes have been changed since the last path rebuild. This can cause problems such as unreachable path nodes, disconnected path networks, illegal paths, etc. which can slow or even crash AI. This error can can be solved by going to the Build menu and rebuilding paths for a map.

Maps need lighting rebuilt

This warning is caused when lighting has been invalidated by moving or modifying a light actor. This can cause problems because the rendered lighting in the level is not accurately representing the current state of lights in the level. This error can be solved by going to the Build menu and rebuilding lighting for a map.

[Actor] bStatic true, but has Physics set to something other than PHYS_None!

This warning is caused when an actor has its bStatic flag set to true but its Physics is set to PHYS_None. Since bStatic means that the actor will not be moving, having Physics set to PHYS_None is contradictory. Actors set with the bStatic flag are also not ticked(updated). This error can be solved by going to the actor's properties and changing its Physics to PHYS_None.

[Actor] is not placeable and should be removed!

This warning is caused when there is a instance of a non-placeable object in a map. Usually this is caused when a object that was originally placeable is changed to be non-placeable. This error can be solved by deleting the object using the map check dialog.

NavigationPoint above level's StallZ!

This warning is caused when there is a navigation point located above Stall Z. Stall Z is used to stop vehicles from flying up to infinity. If a navigation point is placed above Stall Z, it means that AI will try to path to a spot they will be unable to reach. This error can be solved by moving the navigation point below Stall Z or deleting it.

[Component]::[Actor] : Decal's material is NULL

This warning is caused when there is an actor with a decal component that has a "None" material. There will be no rendering details generated for a decal with a "None" material. This can be fixed by going to the property window for the actor assigning a decal material to the decal component.

[Component]::[Actor] : Decal's material is not a DecalMaterial

This warning is caused when there is an actor with a decal component that has a normal material instead of a decal material. This can be an issue because normal materials do not have the extra transformation information to render decals properly and will cause the decal to be deformed at certain angles. This can be fixed by going to the property window for the actor assigning a decal material to the decal component.

[Component]::[Actor] : Decal material [Material] is applied to a static mesh

This warning is caused when the static mesh component of a static mesh actor has a decal material in its 'Materials' array. This can be fixed by going to the property window for the actor, expanding the StaticMeshComponent and Materials properties, finding the named material, and deleting or reassigning it.

[Component]::[Actor] : Material instance [Material] refers to a decal material ([Material]) but is applied to a static mesh

This warning is caused when the static mesh component of a static mesh actor has a material instance in its Materials array that is referring to a decal material. This can be fixed either by reassigning/deleting the mesh actor's component's reference to the material instance, or by reassigning the material instance's reference from a decal material to a normal material.

[Actor] : Ambient sound actor has NULL AudioComponent property - please delete!

This warning is caused when there is a Ambient sound actor with a "None" AudioComponent. It is usually found in older maps where duplication was used to create a actor and can be fixed by deleting the actor causing the warning and creating a new one.

[Actor] : Decal actor has NULL Decal property - please delete!

This warning is caused when there is a decal actor with a "None" decal component. It is usually found in older maps where duplication was used to create a decal actor and can be fixed by deleting the decal actor causing the warning and creating a new one.

[Actor] : SceneCaptureActor actor has NULL SceneCapture property - please delete!

This warning is caused when there is a SceneCaptureActor actor with a "None" SceneCapture component. It is usually found in older maps where duplication was used to create a SceneCaptureActor actor and can be fixed by deleting the SceneCaptureActor causing the warning and creating a new one.

[Actor] : RB_ConstraintActor actor has NULL ConstraintSetup property - please delete!

This warning is caused when there is a RB_ConstraintActor actor with a "None" ConstraintSetup component. It is usually found in older maps where duplication was used to create a RB_ConstraintActor actor and can be fixed by deleting the RB_ConstraintActor causing the warning and creating a new one.

[Actor] : RB_ConstraintActor actor has NULL ConstraintInstance property - please delete!

This warning is caused when there is a RB_ConstraintActor actor with a "None" ConstraintInstance component. It is usually found in older maps where duplication was used to create a RB_ConstraintActor actor and can be fixed by deleting the RB_ConstraintActor causing the warning and creating a new one.

[Actor] : Brush has NULL BrushComponent property - please delete!

This warning is caused when there is a Brush with a "None" ConstraintInstance component. It is usually found in older maps where duplication was used to create a Brush and can be fixed by deleting the Brush causing the warning and creating a new one.

[Actor] : Static mesh actor has NULL StaticMeshComponent property - please delete!

This warning is caused when there is a static mesh actor with a "None" StaticMeshComponent component. It is usually found in older maps where duplication was used to create the actor and can be fixed by deleting the actor causing the warning and creating a new one.

[Actor] : DynamicSMActor has NULL StaticMeshComponent property - please delete!

This warning is caused when there is a DynamicSMActor with a "None" StaticMeshComponent component. It is usually found in older maps where duplication was used to create the actor and can be fixed by deleting the actor causing the warning and creating a new one.

NavigationPoint has NULL CylinderComponent - please delete!

This warning is caused when there is a NavigationPoint with a "None" CylinderComponent. It is usually found in older maps where duplication was used to create the actor and can be fixed by deleting the actor causing the warning and creating a new one.

[Actor] : Light actor has NULL LightComponent property - please delete!

This warning is caused when there is a Light actor with a "None" LightComponent. It is usually found in older maps where duplication was used to create the actor and can be fixed by deleting the actor causing the warning and creating a new one.

[Actor] : Emitter actor has NULL ParticleSystemComponent property - please delete!

This warning is caused when there is a Emitter actor with a "None" ParticleSystemComponent. It is usually found in older maps where duplication was used to create the actor and can be fixed by deleting the actor causing the warning and creating a new one.

[Actor] : KAsset actor has NULL SkeletalMeshComponent property - please delete!

This warning is caused when there is a KAsset actor with a "None" SkeletalMeshComponent . It is usually found in older maps where duplication was used to create the actor and can be fixed by deleting the actor causing the warning and creating a new one.

LevelStreamingVolume is not in the persistent level - please delete

This warning is caused when there is a level streaming volume that does not exist in the persistent level. This can be problematic because the volume will not be considered when checking to see if a streaming level should be loaded or unloaded. You can fix this problem by deleting the level streaming volume and recreating it.

DynamicBlockingVolume does not block players but does block ragdolls (BlockRigidBody is TRUE).

If you have blocking volumes that you turn on during the course of your level, it is important that they initially allow both players and physics objects to pass through. Otherwise, going to ragdoll or using other physics on the player will result in erratic and broken behaviour within that volume.

No or invalid scene capture component - please delete

This warning is caused when there is a PortalTeleporter actor with with a "None" SceneCapturePortalComponent. It is usually found in older maps where duplication was used to create the actor and can be fixed by deleting the actor causing the warning and creating a new one.

FogVolumeActor's Material is not setup to be used with Fog Volumes - please fix or the fog volume will not be rendered correctly / at all.

Materials assigned to actors which are used to define the shape of the fog volume (they are referenced from a FogVolumeDensityInfo's FogVolumeActors array) must have the following properties:

• Lighting Model must be Unlit
• Blend Mode must be Additive, Translucent or Modulative
• bUsedWithFogVolumes must be checked
• An Emissive input must be set

See FogVolumes for more info.

Run 'Clean BSP Materials' to clear [count] references

This warning indicates that there are material references on brush faces that aren't contributing to the BSP, and that applying the Tools->'Clean BSP Materials' operation can clean up these references.

See LevelOptimization for details.