Moronix

I'm sure you are right. Mine is automatic. My manual list several reasons the remote start will not work. The manual says it will chirp the horn when this happens.
Example:
2 chirps Brake is being pressed or the Hood is open
3 chirps one of the vehicles Doors are open
4 chirps Tach not programmed -- see dealer
5 chirps The Key is in the ignition
6 chirps The remote start System is in SERVICE/VALET mode

GoldMustangV6

I've got that on my auto 14. I just hold the button down until the car starts. At first it honks once briefly, then after holding the button still, it honks once more then it starts. The whole process is about 10 seconds long.