The Signal Commander antenna you have (had) on your RV is quite old and you really need to replace it if you have not done so already. I seem to remember that it used the same mount setup as a Winegard but I can't be sure.
If you take a picture of the mounting arms and the bottom of the antenna I could likely tell.
In any case, this is most likely the reason you are getting no reception. You need to replace this with the Sensar III or IV (IV absolutely, but it requires an additional 10" of clearance). When you replace the head you will also need to replace the power supply inside so you get the best performance.