Are you connected up to a 50AMP service connections. Each of the two air conditioner 120VAC power from one of the two power zones from your circuit breaker panel. Both power zones may only get active when you are running from a 50AMP service connection.
Just something to check - I have never played with 50AMP trailers - just going from what I read on here about having two air conditioners installed in trailer.
If you are connected to your house only using a 30AMP RV adapter then it is possible your second zone is not powered up in your trailer.
Also as others have said your 12VDc power should be connected as well to supply power for the thermostats.
just my thoughts
Roy Ken