I looked at the Features for your RV and it suggests that you have separate Cable and Sat. connectors outside (2 fittings). Hopefully then you are connecting the "dish" outside to the Sat input connector and have found the other end of that wire inside and are connecting it to your Sat receiver "dish" input.
You should then be connecting your main TV to the Sat receiver with an HDMI cable. I have a theory that what is going wrong here is that you are also trying to connect your antenna connection (looks something like this)
to your receiver "antenna input" so that the receiver can manage your off-the-air stations as well, but you've mistakenly connected that connection (picture above) to the receiver OUTPUT instead of the antenna input.
If you're not trying to connect your antenna to the receiver, then you should not be connecting that plate (picture above) to the receiver at all (unless the "dish input" is a second connection on that plate).
Can you tell me please which DirecTV receiver model you are using?