I played around with the who-tries event and the open-lock ability, and I have to admit that I failed totally.
What I wanted to do at first was a who-tries event with a must-have value, however, I was not able to find out what a typical value is...
I even used a logic block event to test it and got the impression that all my PCs had a value higher than 0 and smaller than 1.
Perhaps somebody with ADD/FRUA experience can tell me where my mistake is...