I have an application that works.  when exiting, I prompt the user if they
want to back up the data.  If yes, I open a simple form letting the user know
the back-up is in process.  This form uses the timer event and calls a module
that via code compacts the back-end to another location.  I add a date & time
to the end of the file.  This process works well in this situation.  
Something to remember, no open links to the back-end.  Within the module I
also do some other verification.

HTH
SteveD

If this is a second post - oops.
I have an application where upon exit, I prompt the user if the want to
back-up the data.  If yes, I open a simple form indicating the back-up is in
process.  This form has a timer event which calls a module that compacts the
back-end to another location.  I also add the date and time to the file.  
This works well in this situation.

HTH
SteveD
 

If this is posted multiple times - oops.
I have an application where upon exit, I prompt the user if the want to
back-up the data.  This could be your button.  If yes, I open a simple form
indicating the back-up is in process.  This form has a timer event which
calls a module that compacts the back-end to another location.  I also add
the date and time to the file.  This works well in this situation. Something
to remember - no open links to the back-end, the compacting won't work.

HTH
SteveD