If you have a problem with your map being gray and you've created the correct shaders, bitmaps and named textures correctly in max check that you don't have any numbers at all in your material names... Don't ask me why but the radiosity prosses really doesnt like it.. and won't produce your texture.
Hope this helps a few of you ...
If you have a problem with your map being gray....
interestingly, ive found out that you can have all the numbers you want, tool/sapien just removes them. if the left over names conflict then you have a problem, but my textures all worked just fine since they still had different names when the numbers were removed. for example- my concrete02.tif turned into concrete.shader_environment.