Run Custom Action IF Feature is uninstalled.

Hi there,

i just cant get the correct condition together to run a custom action only if a feature is uninstalled.

I have two Custom Actions. One installs a Service needed by the feature "SCREENrec", the other one deletes it.

My Condition for the installation is:
NOT !SCREENrec=3 AND &SCREENrec=3

Which means: IF the Feature IS NOT installed AND WILL BE installed.
Works fine and dandy, will also install the service correctly if the feature is added via "modify".

For uninstallation i reversed the condition:
!SCREENrec=3 AND NOT &SCREENrec=3

Which should mean: IF the feature IS installed and WILL NOT BE installed.

However, the problem is that, if i install the feature on first time install. It will correctly install the service.
Then i open the modify function and add another feature, (not touching the SCREENrec), it will trigger the uninstall action!
WHY?

Could someone please give me a condition to execute if a specific feature will be installed or will be uninstalled?
Google wasn't quite helpfull..

Thanks in advance,
Johann