I can't get correct alpha channel when rndering transparent objects with VRay 3

[magnoliatf]

I try to render a model in witch every wall is made of glass. But in the alpha channel, it appears like all the things behind the glass do not exist. Just like the pictures show. The materials I use are from the material library. Did I miss something?

Thanks for every one willing to help!(○?ω?○)

[peerman]

Check if you have flipped normals? I also believe there's a setting somewhere for alpha contribution. Maybe that's a setting you can play with.

Best