I just had a similar problem with my Jayco Greyhawk.  We are getting ready for a Florida trip.  I had the unit hooked up to shore power in my drive.  When I went to start up for a shakedown drive, there was no power to start the engine.  Used the "emergency" button and the coach batteries started the engine fine.  I took it to the dealer and explained my problem.  I was told that the chassis battery only charges when the alternator is working i.e. when the engine is running.  They said that I needed to put a trickle charger on the chassis battery when I shut down for a month or so.