InstallAware

My script writes to the registry during first-time installations then reads this registry entry when the "Modify" option is selected during "Maintenance" installs. I set the "Permanent" option in the "Write Registry" dialog but it doesn't prevent my registry entry from being deleted by the Maintenance install. The result: subsequent maintenance mode installs don't behave the way I want because the registry entry is no longer available. What am I missing here? The help system describes this option as: Check this field to never remove a registry entry once it has been recorded using this command. The registry entry will survive uninstalling the product, or changing the installed feature set. The entry does indeed survive uninstalling but does not survive changing the feature set! What's up with this?

Please give the steps to recreate this, because I just tried it, and it works as expected.