@Superku: When I do that, I can see the effects of the normal maps on the models, but the level geometry is just flat.

@painkiller: I'm using the textures in a Wad file... with the "_n" at the end of the normal map texture file name.. So in my WAD, let's say I have two textures in it, one is the regular texture, the other is the normal map. I applied the regular texture to the level geometry and set the mtl_Bump material on it. So it should apply the normal map automatically right?