on will close theObject

In the past (when using 10.3) I have used “on will close theObject” (theObject being the main app window) to save my table data to a file upon quitting out of the app. It doesn’t seem to be working anymore now that I rebuilt the app in 10.4.

Any thoughts or alternative suggestions would be greatly appreciated,
CarbonQuark

BTW, I have tested the actual code used to save the file using “on clicked theObject” and that works fine. It has to be something about “on will close theObject”.