Your issue is probably number 11 from
this list of issues
11. Rainbow/question mark texture on my object
The game doesn't recognize the texture.
This can be caused by a missing spec/bump, wrong texture size, or an unwanted alpha.
This problem can be fixed by resizing your diffuse image (the main texture image) so that it has sides that are 64, 128, 256, 512, or 1024. The image can be rectangular or square, but each side needs to be one of those numbers. If your diffuse image is already sized correctly, make sure you have not removed a necessary image or included an alpha image where an alpha is not needed.
