Application Onkey Problems

Hi,

I have a small problem and was hoping someone could point me in the right direction.

I'm just looking to prevent users from using the print screen or the alt print screen buttons on the keyboard. I have this script that works if I use "39" (Right Arrow)but wont work if I use "42" (Print Screen Button) any ideas why?

Thank You, Mike

Private Sub Workbook_Activate()
      Application.OnKey "{42}", "TEST"
   End Sub
Private Sub Workbook_Deactivate()
    Application.OnKey "42"
End Sub