Well, the thing that jumps out at me is that you don't have a fixed number of trials, not fixed number of trials. You could say each trial, each roll is a trial. Success is getting a double, which has a fixed probability. Whether or not you get a double on each trial is gonna be independent of the previous roll. So it meets all the other constraints, but it does not meet that there's a fixed number of trials. You're gonna keep someone, there's some chance you might have to roll 20 times, or 200 times, or who knows however many times, until they roll a double. And so this violates there's a fixed number of trials.