title: adding users to ADGroupMember with userPrincipalName
body: <p>I am trying to add a group of users to ad group having only userPrincipalName.</p>
  
  <pre><code>Import-Csv "C:\Temp\TESTGroup.csv" | %{ Add-ADGroupMember "Group Name" $_.userprincipalname} 
  </code></pre>
  
  <p>This results in an error message relating to <code>$_.userprincipalname</code></p>
  
  <p>I want to add a group of about 65 people to this AD Group.</p>