I am not familiar with your set up but do know that there has to be an uninterrupted coax circuit from the dish to the receiver. If the rv circuit / receptacle you are using branches off to the rv antenna it will not work. Try running your dish coax directly to the receiver through the door. If you then receive signal, you have confirmed what I am saying. If this is the case, you may need to install a separate dedicated sat receptacle on the outside to feed the receiver.
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.