1. I create a layered texure with 3 layers.
2. I use 3d paint tool to create 2 black-n-white textures.
3. I assign 1 of the b&w textures to the alpha of the top layer of the layered texture.
4. I assign the other b&w texture to the alpha of the middle layer of the layered texture.
5. I render out in Maya Software, I can see all 3 layers.
6. I render out in Mental Ray, I can only see the top 2 layers.

Other people I know have the same result. Works with Software but not with MR. I've played around with alot of settings and searched Maya Help but I haven't come up with a reason yet. Anybody know why it won't work in MR? I've attached luminence nodes to the b&w textures. I've even set them to "alpha is luminance", etc. The texture sample looks fine, just doesn't render out properly in MR.