I want to create a macro that will be called when I input a certain word into a cell. (Actually, the text will be entered using a validation list.)

Here is the code that I have, but it doesn't do anything.
Code:
Private Sub WorkSheet_Change(ByVal Target As Range)
Select Case Target.Address
      Case "$A$2"
            Select Case Target
                 Case "Partsbook"
                      Call Partsbook
                 Case "RPL"
                      Call RPL
                 Case "O& MM"
                      Call OMM
                 Case Else
             End Select
      Case Else
End Select
End Sub