Thanks a lot R0J0hound!
I tried it the way you suggested, but Else does not work on triggered events :(..
So i tried 'key is down' instead of 'on key pressed', which worked, but also caused the switch to permanently change its state. I got it to work now adding a system 'wait' (for 0.2 seconds) to my former settings and now it works.
You and the whole Construct2-Community are great!
:D