VFP6.0

In my application I use .mem files to track various identifing numbers like so..

RESTORE from customercounter.mem additive
nextcustomer = customercounter + 1
REPLACE customerid with nextcustomer
SET safety off
customercounter = nextcustomer
SAVE to customercounter.mem all like customercounter
SET safety on

This works fine when I run the application from the project window, but when I Build the .exe and run it, it stops working.

WHY, and is there a better way to do this?