i'm completely foxed by a height detection condition...

[filth]

hello wonderful ofpec people.  here's my problem: 
i want to fly a chopper into a zone and have a trigger fire when said chopper is on the ground within that zone. 
what i have in my trigger is 'vehicle present' and in my condition line is thus: this && getpos chinook1 select 2 < 1.  now, this works perfectly if i'm in the chopper at the start of the mission, but if i board the chopper during the mission and then try to activate the trigger... it doesn't fire. nothing... nadda... not a bloody sausage. any idea why? (the chopper is definitely named chinook1).

EDIT - think i may have solved it by myself. i was using a bas chinook as the aircraft, which must have a bug because the normal bis chinook works perfectly. as you were. thx.