truck won't start when the alarm is on?

My problem is ..this usually happens in the cold weather also, The truck won't start when the alarm is on ..the alarm is factory ..the radio says theft lock ..I do not know if theft lock is the same as the passlock security system .. everything works properly..it acts as though the security system is not letting the truck start..lights work everything else works ,btu it wont turn over..when I keep the alarm off i dont seem to have a problem at all...any answers to this problem would be greatly appreciated..Thank You