key detection in user forms
 

I am writing an MSAccess simulator in Excel 2007 under Vista. In a form with
5 rows each of 6 buttons I want to be able to detect the pressing of
Up,Down,Left and Right keys.
I have tried all 3 methods (Private Sub UserForm_KeyDown,
_KeyPress and _KeyUp) and I can prove these are not working because I have
added a Stop statement as the first line of code in each,
and these are never executed.
Neither does it help to use a separate set of _keyUp etc for the individual
buttons.
Has anyone out there met this problem and/or solved it?
Please help if you can.