You probably have a small HDTV in your house with a remote.. Move it out to the trailer and see if that works ok... My OFF-ROAD Camper HDTV is a VIZIO 22-inch model... When we are OFF-ROAD camping I use a small wattage PSW POWER INVERTER to run my 120VAC home entertainment items...
Like was discussed above the digital TV is either great or nothing at all so this present you with the problem you really have to know where to point it... Its not like the old analog days where you just turn the antenna and see some weak signal then you can can peak up on it. With the digital TV you have to be right on the signal first to get it to scan into the HDTV electronics...
I have one of those SURELOCK meters that you can install in the RG line and when the antenna is pointed right you can peak it up using those green lights coming on by using the ADJ knob and get right on the main HDTV signal..

There are different type of signal strength meters you can use...
I would swap a few things out with things that work somewhere else and find out where the problem is... The WINEGARD needs +12VDC to operate its built-in pre-amplifier... If you gots a multimeter you can measure for this DC voltage on the end of the RG cable to make sure it is there.
Good luck getting it all going... Should start falling into place with all these good folks on here giving great ideas... I always like to figure all of these things out at home so I don't get caught out off the road somewhere and find something was wrong all along...
This is what my OFF-ROAD POPUP camper looks like camping off grid watching HDTV digital signals... I like to keep tabs on the bad WX when camping in my POPUP trailer... Also like to watch NCIS and WALKER-Texas Ranger haha...

Roy Ken