White Faces Error

I am using Blender to make 3d assets for a game, but I have a problem. On some of the meshs there is a few faces which will not show a texture.

I have tried to delete the bad faces and rebuilding them, and flipping the faces and recalculating them but it does not work. How do I fix this problem?

Could you post the blend file? That makes it easier to track the problem