Ascend Max 2000 and Radius

I am trying to get an Ascend Max 2000 to work as our in coming modem pool. It requires Radius for authentication. We have a Win2K domain using AD, and I have setup one of the DC’s to be an IAS server. The problem I am having is when I login the DC authenticates me (or so the event log says). But on my dial-up networking client I get a 691 error, which states that I have not been authenticated. What?s the deal! I believe I have the modem pool configured correctly it just seems as though the Radius (IAS server) is not communicating with the Max 2000.