Without seeing your entire WiX file, it will be
hard to tell you what is going wrong. There are
many elements which may be blocking it. But from
what it sounds like, I don't think the custom
action is firing in the case overinstall.
In my other answer to your other question which
got you this far, I suggested putting:
In your customAction. This is exactly the
reason - for debugging. In the SECOND time you
run the installer, do you see those lines (for
Begin and End) in the output log?
Lastly, a tool that might help you will be the
That tool will let you open your msi file, and
see all the configurations that were setup. So
you can see if there is a condition set for your
custom action being called.