Light problem. Please HELP!

Why is this point light doing this? It only is lighting part of the ceiling while the other part is black. Can anyone offer any possible solutions? The mesh for this cell contains 8 vertices which make up 4 faces: 1 face for the ceiling, 1 for the floor and 1 for each of the two walls. Does the mesh need to be subdivided further? This is very discouraging. I got better results using GameMaker 8.1 with Ultimate3d dll., and that’s laughable because Gamemaker is really NOT a 3d engine. I know it is probably something simple. The material for the mesh contains textures for color, occlusion, specularity and a normals map. I have other meshes for other cell types (corners, dead ends, T’s, etc.) and they are all very basic variations of this same basic cube, but they all do something weird with the point light. When I use the mesh I made for a corner, the whole ceiling lights up fine except in one spot where I get a black circle. I have tried removing The spec and occlusion from the material, but nothing changes. There is no slope in the ceiling and the point light is positioned slightly below the ceiling.

Any ideas?