Here is a pictorial showing how to use the Antenna WALL PLATE box...


Google images
Also be sure you have selected ANTENNA on your HDTV scan setup... Also if the antenna is the BATWING style you have to have it pointed at the HDTV digital transmitter antenna location...
The BATWING antenna i have looks like this - NOTE the dipoles on the front...

Google Image
If your winegard is one of those omni small round antennas have heard they are not very good except for real close HDTV stations...
Looks like this and is mounted real close to the roof...

Google Image
Let us all know how you are coming along...
I use my BATWING antenna up a short pole on the side of my POPUP trailer and it picks up very well in my OFF-GRID locations...

Roy's image
Roy Ken