What TV are you trying to listen to? Note that only the main room one is connected I believe.
Check the back of the TV for red/white RCA cables. these are hardwired into the TV speaker and should be connected. the main TV speaker needs to be on... sound will come from both the main TV and there overhead stereo.
If RCA being the TV is connected you may need to pull the head unit and verify that they are connected in the back as well. You should have received 2 little radio removal keys in your airstream package when you got your trailer. they look like thin metal bars.
If not you can order some on eBay for $5. The radio slides out after you unlock it with the keys that slide in either side of the radio face.
You can also get at the RCA connections by removing the interior panel in your overhead cabinet. its a rats nest back there though - you need to look for the red / white RCA wires