RDM on Citrix

Hi,

I have a problem with the RDM:
We are running the RDM (6.6.0.0) on our Citrix XenApp 6 Server. When I access it from any Windows maschine (either by Webinterface or Online Plugin) it works fine.
When I try to access the Application from my Mac (latest OS X and Citrix Receiver installed) it does not pass thru the keyboard inputs to the managed maschines. Mouse actions are directed to the maschines.
When I access the maschines directly with mstsc (also published on the Citrix Server) it does work.
Is there anything I can check?