If it is not labeled on the outside of your rig at the connector as "Sat" or "SAT TV" then yours is not rigged for satellite.
Doing so requires one single continuous coax run of RG6(?) direct from your SATBOX through the trailer to the satellite dish. You cannot just plug it into the "CABLE" input as that is junctioned with the antenna and the cable run.
Below is a link to a great site which discusses how to modify your setup.
http://www.modmyrv.com/2008/06/17/rv...cable-rewiring