I'm posting my scene file so that someone might be able to take a look at it and help me out.
I also want to comment on my experience with building shaders with mental ray vs mantra/renderman. Mental Ray in Maya is an attempt at a artist friendly renderer, but at the same time is extremely difficult to construct something beyond the basic functionality of the shader unless you learn its overly complex shading language. Why does everything have to be a hack? I wish that they would implement a solution to allow an artist to create a complex shading network without having to spend time finding work arounds. Something like VEX SHOPS in Houdini. Just my thoughts!