Compiler variable substitution in debug mode

[IntelliServ]

I'm trying to use a compiler variable to set my PRODUCTCODE. I do this by filling the Product Code text box (from Visual->Application Information->Project Properties) with #USEPRODUCTCODE#. This seems to work fine normally. When I do a debug build and run it in the UI then it doesn't seem to set the Product Code correctly. A debug build run outside the UI works fine. And assigning another variable such as "Set Variable Jimmy to #USEPRODUCTCODE#" works fine. I break early in the script and look at PRODUCTCODE and Jimmy in the variable watcher window. PRODUCTCODE's value is "#USEPRODUCTCODE#" while Jimmy's value is the valid product code.

The main ramification of this is that if I install a product and then try to upgrade that product by running a new installer in debug mode then it doesn't detect that a previous version was installed. Could someone please explain why InstallAware behaves this way or explain a better way to set the Product Code at compile time?