Error while running Access MDE

Hello Friends,

I am having a problem running an Access MDE file. When I
select a value in a particular combo box, I get the
following error message:

The expression After Update you entered as the event
property setting produced the following error:
*The expression may not result in the name of a macro, the
name of a user defined function, or [Event Procedure].
*There may have been an error evaluating the function,
event or macro.

This error doesn't show up while trying to use the same
combo box while using the .mdb. It only occurs in the mde
version which has been recently made from the latest mdb.

Any ideas??

Thanks & Regards,
Hemil.