If I'm not mistaken, the basic plane mesh has the same qualities as the ceiling mesh, which is only visible on one side. 'Ave ye looked at it at all angles, moving it 'round and rotating it?
Or do ye mean the mesh does not 'ave the retexture on it? If that's the case, try exporting it with a different texture and test it in the map y'er making. It could just be an export glitch, or the texture y'er using may be the issue.