Osyr

Hi, I'm trying to execute WHEN ALTITUDE > BODY:ATM:HEIGHT THEN { AG1 ON. }. and getting "Flagrant error on line 0." The same for the line PRINT ship:mass * body:mu / (ship:maxthrust * (body:radius + altitude) * (body:radius + altitude)). but when I write SET m TO ship:mass. PRINT m * body:mu / (ship:maxthrust * (body:radius + altitude) * (body:radius + altitude)). it works. Can anyone tell me what's wrong?