Cannot access windows server 2008 r2 terminalserver

Hello,

i´ve just installed a windows server 2008 r2 device. Then i tried to access this server with an zen 7 terminal server object from a windows xp client. Access was no problem. Then i added remote desktop host role to this server 2008.
Now, the zen 7 terminal server objects is not able to access this server anymore(remote computer was not found).
If i use the remote desktop client i can access this host without problems..
Any idea?

Thanks
Sven