After I build a misson and try to save it or play it this message window comes up.cheifo_cheif only has 1 weapon.What is wrong.Thanks

Moved to the Mission Builder forum where you might get more help.

Are you sure the error reads 'only one weapon?'
Not, perhaps, 'only one waypoint?'
This waypoint error is the more common one. It smply means that somewhere in the mission, you have created a moving vehicle with only one 'start' waypoint. For any moving vehicle, you need at least one more waypoint to avoid this message....
Hope that sorts your problem, otherwise check back here again...

bigbossmalone is correct, but I believe one of the truck convoys also occasionally creates this error even when there is more than one waypoint. I think it was a Russian convoy, but I could be wrong. You must delete that convoy and not use it in the mission.