It could be a bad cable. The new digital TVs are very sensitive to weak signals. The pictures don't get snowy when the signal is weak, they just go away. Check the cable between the set and the wall to look for wire whiskers between the body of the connector and the center wire. Check to be sure the center wire is there, and is long enough to be even with the threaded part of the connector. I had one that had pushed back into the short cable and wasn't making a good connection. Sometimes it would, sometimes it wouldn't. If someone has added a splitter in line with one of the TVs, the weaker stations may not be detected by that set. My trailer had a splitter at one of the two bedroom outlets that fed the two outlets in the bedroom. The signal at those two TVs was half the strength of the living area set. Probably not your problem, but could depend on how your trailer is wired. If the plate with the CABLE/ANTENNA switch is in the living area probably not but if it is in the BR, maybe....
You cannot reason someone out of a position they have not been reasoned into"
Al, K5TAN and Missy, N4RGO WBCCI 1322
2002 Classic 30 Slideout -S/OS #004
2013 Dodge 2500 Laramie 4x4 Megacab Cummins