Welcome to the forum!
Does your coach have the sucky Seiki TVs? If so, they won't work with some cable systems, as they don't have a QAM tuner built in. I have replaced one of my TVs because I had that problem at several parks, then had stays at many parks with no problems. It all has to do with the cable systems, the older ones arent a problem.
This has been thoroughly discussed here many times. A quick search will give you hours of reading. Many have replaced the Seikis with smart TVs. They are pretty cheap and much more useful. My removed Seiki works ok on my home cable system, but is still sucky!
My splitter was behind the microwaye and most of the connections were a bit loose. Also, there is the booster button for antenna TV, which will screw up the cable signal. You probably already knew that.
If all else fails, read the directions!!