How to make a clipmap visible in ray mirror?

I have modelled a park with buildings in it. For trees I used bitmap tree pictures with an alpa channel. The trees look great, but when looking into the glass of the building the trees don’t show at all! Is there a way to make the ray mirrored glass reflect the trees?

On the other hand the clipmap I used to cast shadow (separate object which faces the sun) appears as a grey/black surface in the glass, any ideas to make them invisible?