Unknown user type while using AcquireTokenAsync with UserCredential
<p>I used AcquireTokenAsync for authenticating with Azure Active directory.</p>

<p>below is the code</p>

<pre><code>var uc = new UserCredential(username, password);
var s =  var s = await authenticationContext.AcquireTokenAsync("https://graph.windows.net", _clientId, uc);
</code></pre>

<p>the problem is that when I run the code, I get </p>

<blockquote>
  <p>"unknown_user_type: Unknown User Type"</p>
</blockquote>