title: Active Directory different results for DirectorySearcher and PrincipalSearcher
body: <p>I have strange problem when querying Active Directory in C#.</p>
  
  <pre><code>var ctx = new PrincipalContext(ContextType.Domain, "adr", "usr", "pwd");
  var entry = new DirectoryEntry("LDAP://" + adr, usr, pwd);
  
  var searcher = new DirectorySearcher(entry) { Filter = "(&amp;(sAMAccountName=user_to_search))", PageSize = 2000 };
  
  foreach (SearchResult searchUser in searcher.FindAll())
  {
      // groups
      var groups = searchUser.GetPropertyValues("memberof");
  }
  
  var groups = UserPrincipal.FindByIdentity(ctx, "usr_to_search").GetGroups(ctx).ToList();
  </code></pre>
  
  <p>But the results are not the same: </p>
  
  <ul>
  <li>the <code>PrincipalSearcher</code> returns 14 groups </li>
  <li>the <code>DirectorySearcher</code> returns 12 groups</li>
  </ul>
  
  <p>Well, is this bug or did I miss something?</p>
  
  <p>Thanks</p>