Oookay, so I have a tank with a 50% probability of presence. It starts empty, with the crew monkeying around nearby. Now, if there's no tank obviously there's no need for a crew, so I assumed that a condition made true only if the tank appears could be used in the 'condition of presence' field of the crewmen.
So I stuck tankpresent = true in the init field of the tank, and used tankpresent as the condition of presence....no dice. There seems to be no connection between the two.
I'd like to keep this as simple as possible (and I bet the solution is) but right now my brain is fried....somebody 'splain this please.