[Observium] Radius Auth on Win2k8 NPS - malformed message

Hi,

I try to configure observium with radius auth against a (working) win2k8 NPS Server; this failes with the follwing error message on the server: "A malformed RADIUS message was received from client %1. The data is the RADIUS message."

http://technet.microsoft.com/en-us/library/cc735403%28v=ws.10%29.aspx

Any hints why radius auth doesn´t work in Observium?

Chris