Easy Question: Trigger being activated when an entire group is in a vehicle

[Ding]

This is a very easy question that I feel stupid not being able to work out myself, What do I put in the condition of a trigger to set it off once an entire group is in a vehicle?

I've tried:

Code: [Select]

units Group1 in Truck1
as well as a number of variations on that, would prefer not to have to use a script file to do this, it's really annoying me as I don't want to name each of the group member either and I know that it's something simple that i've just forgotten.

edit: managed to work it out eventually, have not edited in OFP in a while and forgot 

Code: [Select]

(count units aP1) == ("_x in T1" count units ap1)
that worked fine, locking topic