I realize this thread is almost a year old, but we've found that if there isn't enough space on c in the %temp% dir, the installer just cannot recover. Found this: http://kb.flexerasoftware.com/selfservice/viewContent.do?externalID=Q105366
You're looking for a result of your dialog. Something like this should work for you, I just took a code snippet from one of our projects:///////////////////////////////////////////////////////////////////////////////// ...
I can't say for sure, but try setting your Min/Maximum Version to what your product is, and then the next installer change the min/max to what that currently is.As long as the upgrade code is the same, it should see that it's there, but can't upgrade...
InstallShield likes to use it's own names for paths. I always end up editing them on my own in the 'Direct Editor' to keep things clean. Check under your 'Path Variables' for what it's defined.