Sounds like you don't have enough Ray Depth (and Reflection Depth) set up.
If you go in to Detailed Settings for Cinerender, go to Options > General Options.
Here you can set Ray Treshold, Ray Depth and Reflection Depth.
Ray Treshold is percentage that controls as a cut off for brightness. Rays that fall below the treshold will not be considered for reflections.
Ray Depth and Reflection Depth have a counter for layers of transparancy. It sets how many layers the rays will pass through to show transparancy and to show reflections on the transparant surface. So a setting of 3 would allow the rays to pass through a single solid glass surface and show what is behind this. For this reason you want something around 12-15 generally, to allow it to pass through several layers of glass and show your alpha channel transparancy on the trees.
Erwin Edel, Project Lead, Leloup Architecten
www.leloup.nlArchiCAD 9-26NED FULL
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