Some materials aren't rendered in the Blender Game Engine As I described in the title, some materials aren't rendered. I'm not sure, but I think it only happens if I "copy paste" or append objects with their materials. I can solve this problem by recreating the broken materials (but this is a tedious task).

The materials are visible in textured viewport. Only when I  start the BGE they are invisible.

Here you can Download the .blend:

Download 

(it is a car game. on the left is a text editor where I describe the problem again)



in this picture you can see the Material which disappears.

Thanks
I am having the same problem. Best solution I could find (more like a workarround) is to apply all the modifiers of the object which is causing trouble (in our case, it is Luftauslassheck).

Should you find out what is happening, please let me know. Here is a link to my blend if you want to take a look at it. The object is Support.Cover, which only has the material PlasticMaterial.002, used in other objects as well.

Nice car model by the way