Ok. Seems like i have a bug with alpha channel here.
This is the render and alpha channel from this render. And there, on glass-material forms is some black and white distortions in alpha channel. But there everything should be white in alpha. There is certainly no holes in geometry and the material is a simple coloured glass.
Is that bug or what? Seems like the material is reflecting black alpha from surrounding.
PS. And this bug is on every picture with this glass-shapes.
Build timestamp: Jun 18 2014 21:45:36
Corona version: Daily build post-A6, Maxsdk version: 2014
3ds Max 2014 x64 SP5