When your a/c selector switch is set to run both a/c units, the front and rear air units both should run on shore power as long as the 30 amp and 20 amp connections to the power pole are not on the same circuit. Most power poles that are set up for 50 amp service should work ok.
Here is a link to my DIY install of the
dual power adapter for my 30 amp coach. Maybe it will be of some help?
edit; One more thing, check the built in circuit breaker on the dual power adapter, maybe it was turned off accidentally, it has a maunal on/off switch