I suspect you have an open in your RG COAX somewhere... CB radio should receive off of any antenna wire you can stick in it...
Try any wire for a test... If you got an old yank of RG cable with the RG connector for your CB - screw that into your CB and then just strip back the other end four or five feet with just the inner conductor showing. Throw this out your vent window... This will almost be as good as your high dollar antenna will work on receive... Try this for a test... This will tell you your CB radio is receiving OK... Once you know the CB is receiving OK then you can start looking into the antenna you just installed. Something wrong with that...
I have a CB under my truck seat on CH19 with the squelch turned up all the way. I use this just to monitor the truckers in my near vicinity for road traffic info... I can't remember the last time I transmitted on it... Since being involved with RVs since 2009 I have never heard another RV CB conversation... We use cell phones mostly and also have a couple of FRS radios to use around the camp site...
The CB truckers are still just as nasty speaking as they were 20 years ago... It still is the best way to learn about what is happening close to your location however on the big roads... Most Truckers are outdoor type folks and I occasionally hear a comment between two truckers saying "did you see that off-road POPUP. We could do some great deer hunting in that"...
Roy Ken
ADDED NOTE : I see you listed using a CB ANTENNA rated for a 1000WATT rating. This of course is an illegal use for the 27Mhz band CB radio's. It is also a heavy duty construction of the CB Antenna which may give you more things to break down on you. Something inside this antenna may have been burned out for instance from running high power...
Your listed CB radio will only produce around 3-4 WATTS RF Output at the base of the CB antenna.
Roy Ken