On my motorhome, I have a Winegard SK-3005 antenna. Originally it was a non-SWM setup and worked well with my 2 DVRs. I changed to a SWM so I could use both tuners on the DVRs. I have quadruple checked my installation with the SWM-8, power inserter and splitter but I get an error upon setup of the dish. Local channels and many of the upper channels come in but not all. I get a 771 error on those that don't display. Is this something in my installation or is the Winegard not working properly?