title: Error with PrincipalPermission authentication in WCF
body: <p>I am following a <a href="http://www.pluralsight-training.net/microsoft/courses/TableOfContents?courseName=wcf-design-concepts&amp;highlight=aaron-skonnard_serialization%2a1" rel="nofollow">Pluralsight video on Authentication</a>.</p>
  
  <p>I am trying to add simple PrinciplePermission authentication to my web service:</p>
  
  <pre><code>    [PrincipalPermission(SecurityAction.Demand, Role = "Computer\\Group")]
      public String testDBConnection()
      {
          return "success";  
      }
  </code></pre>
  
  <p>In my WCF client I am sending:</p>
  
  <pre><code>    client.ClientCredentials.UserName.UserName = "Alice";
      client.ClientCredentials.UserName.Password = "alice";
  </code></pre>
  
  <p>I have created the group and added Alice to it as per the video, but now....</p>
  
  <p>I keep getting the error:</p>
  
  <p><strong>"Request for principal permission failed."</strong></p>
  
  <p>Any idea what's wrong?</p>