[8.960][OPEN] HTML5 VPN rdp connection throws an error

Hi,
I currently get an internal server error after connecting the HTML 5 RDP session.

below the logging but it seems the error message is empty.

2012:05:29-15:39:39 ranger screenmgr[5113]: Client 10: disconnected: Broken pipe
2012:05:29-15:40:37 ranger screenmgr[5113]: Client 11: authenticated: user='bert'
2012:05:29-15:40:37 ranger screenmgr[5113]: Client 11: start screen requested: REF_CliConRdpDelta
2012:05:29-15:40:38 ranger screenmgr[5113]: Session[11]: Service has stopped with an error:
2012:05:29-15:40:38 ranger screenmgr[5113]: id="2202" username="bert" event="Connection stopped" sub="vpn" variant="clv" sys="SecureNet" severity="info" srcip="77.222.76.132" service="HTML5 VPN" type="VNCRDesktop" sessionid="11" sessionname="RDP Delta"