OnLoginFailed AxMSTSCLib.AxMsRdpClient8NotSafeForScripting

That one is called MSTSCLib, without the Ax for ActiveX at the front (and I get better results with that search):

http://msdn.microsoft.com/en-us/library/aa383022%28VS.85%29.aspx

Sound like an ActiveX based API for the Remote Desktop Protokoll.

From what I read while looking there, it could be that the Connection atempt is not a Blocking call. So you perhaps expect the Event to be raised instantly after/during the atempt, when it actually needs some time.

Or maybe this Event is only for Network based problems during Logon, not for User Credentials based Problems during Logon.

---

Let's talk about MVVM: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/b1a8bf14-4acd-4d77-9df8-bdb95b02dbe2