How to change TS_RESPONSIBLE field when test copied

Hi,

I am trying to auto populate the TS_RESPONSIBLE field in Test Plan with the users name that has copied and pasted an existing test to a new location within the Test plan Tree.

I have tried

Function ActionCanExecute(ActionName)

  On Error Resume Next

If ActionName = "act_paste_Branch" Then
   Test_Fields.Field("TS_RESPONSIBLE").Value = User.UserName
End If
  On Error GoTo 0

End Function

 and have tried

Function ActionCanExecute(ActionName)

  On Error Resume Next

If ActionName = "TestPlanTree.Paste" Then
   Test_Fields.Field("TS_RESPONSIBLE").Value = User.UserName
End If
  On Error GoTo 0

End Function

Any suggestions?

Cheers

Justin