Hi, OssieMac:

You are exactly right.

Firstly, the combo box was one created from the Forms Tool bar and not
one created from the Control Tool Box toolbar.
Secondly, I already set the combo box to be linked to cell B1 (index
of the selection from the combo box).
Finally, whenever I change the selection from the combo box, I just
want a WARNING message popping up and the response to the message is
always "ok". In other words, if I click the combo box but I don't
change the PREVIOUS selection, I DON'T need the message box.

If you can modify your code, it will be great. Your efforts are highly
appreciated!

Thanks again,