wireless HDMI transmitter/receiver issue

Hi. I currently have in our camper a wireless transmitter/receiver from the satellite set-top box that mirrors the signal to a TV out on our deck.  It worked flawlessly until recently.  It's beginning to have a few issues.  I decided to buy a new set with more wireless receivers to mirror to the camper bedroom TV, also.  The new set would not transmit the signal from the satellite set-top box.  Just got a blue screen.  So I tested the set by hooking up the transmitter to a DVD player.  Worked flawlessly.  I thought it might be an HDCP issue, so I got an HDMI splitter that bypasses HDCP.  Didn't work.  So I bought a 2nd transmitter/receiver set.  Same issue with the blue screen, yet works with the DVD player.  I brought the two sets home to try it on our set-top box at home.  Both transmitter/receiver sets work flawlessly at home.  Any clue why they will not work with the set-top box at the camper when the original one works?  The camper set-top box is an HR24-500.  I've compared setting on both set-top boxes, and they are the same.  Please help!