One of those two outlets are a direct feed to the park cable/satellite connection on the outside. That is the one you want to feed to your box to have direct isolated feed from the dish to the box.
The other outlet on the dual receptacle runs to the rv antenna circuit.
If neither one of those work, try running coax from Sat directly to the receiver through the door. If satellite reception works, then you may have a faulty cable connection from the outside receptacle.
Steve Rinker
Rochester, NY
2013 Keystone Sydney 340FBH 5th Wheel, 12,280 lbs loaded (scale)
2015.5 GMC Sierra Denali 3500, SRW, Duramax, CC, Payload 3,700 (sticker- not scaled yet)
Take my posts for what they are, opinions based on my own experiences.