Grimrock

I made a tileset. But somehow it gives me the following error.. what is causing this?
(made tilesets before, but don't understand what I am doing wrong with this ceiling ?
Trying to figure out why he is asking for a ceiling with _0101 ... has this to do with the dungeon builder? variations?

=== Software Failure ===

[string "Arch.lua"]:0: undefined object: dscb_catacomb_ceiling_0101
stack traceback:
[C]: in function 'error'
[string "Arch.lua"]: in function 'findArch'
[string "Arch.lua"]: in function 'spawn'
[string "DungeonBuilder.lua"]: in function 'buildLevel'
[string "Map.lua"]: in function 'loadLayer'
[string "Dungeon.lua"]: in function 'loadLayer'
preview:113: in main chunk
[string "Dungeon.lua"]: in function 'loadDungeonFile'
[string "DungeonEditor.lua"]: in function 'playPreview'
[string "DungeonEditor.lua"]: in function 'previewButtons'
[string "DungeonEditor.lua"]: in function 'update'
[string "Grimrock.lua"]: in main chunk

I've seen something like this before. In that case it turned out to be the line "ceilingEdgeVariations = true," in the tile set definition, and removing this line fixed the problem.
Hope this helps.

The ceiling edge variations have to do with the castle and dungeon arches; as they can either have open arches, or closed, and have many variations defined.
The 0's and 1's indicate open or closed arches in the asset model. You can find them in editor, and the asset pack model directory. The definitions in the dungeon and castle lua files.

Specifically, for ceiling textures that have variants, the 4 numbers correspond to extra "flaps"of texture that fill the arch's gap in the walls. You only want these on walls though. if you have the flaps in open areas of ceiling you will see them hanging down and look bad. So the numbers correspond to which sides of the texture to put the flaps. The texture must be facing north (0) and then the four numbers follow the compass, starting at north, east, south, west. A 1 shows the flap on that side, a 0 will not.