NotSupportedException.....from ascyn webservice call?

[Iceman_Aragorn]

Below is the offending code. The error occurs in the last line, when
the endauthenticate1 method is called. The "ar" webclientasyncresult
variable, at this point, contains a property called error which
contains "NotSupportedException".
Any ideas as to what could possibly cause this?

IAsyncResult ar = securityProvider.BeginAuthenticate1(username,
password, jndiNotNull,SecurityPlatformProviderService.getJndiName(),
null, null);

int secondsToWait = 0;
while (!ar.IsCompleted)
{
// do work while waiting
if (secondsToWait++ > securityProvider.Timeout/1000)
{
//abort the webservice as we timed out
((WebClientAsyncResult)ar).Abort();

//throw a new web service timeout exception
throw new WebException("Login Failed - Timeout",
System.Net.WebExceptionStatus.Timeout);
}
else
Thread.Sleep(1000);
}

return securityProvider.EndAuthenticate1(ar);

 

[Iceman_Aragorn]

For some reason, syncronous calls too, result in a not supported
exception.