I think we're all just guessing. Unless you can post a picture or a brand and model number for the "rocker switch" I don't think you're going to get much help. With 3 wires, one might go to the TV, one to the park's cable and the other to the OTA antenna. Not knowing your particular setup, there's no way of knowing. If the switch is as I described, then not having any power at the switch would be normal. The power supply for your crank-up OTA antenna is somewhere else. Try tracing the wires or bypassing the switch with the two wires feeding it by connecting them directly to the TV.
For better help, a picture or some way of identifying what you've got will get you better help.
Don Ford
2004 Safari Trek 31SBD (F53/V10 20,500GVW)
'09 HHR 2LT or '97 Aerostar MiniVan (Remco driveshaft disconnect) for Towed vehicles
BlueOx Aventa II Towbar - ReadyBrake Inertia Brake System