I agree with Seadog, Need clearer description but I'll throw some info at you making some assumptions. By saying the TV in the toyhauler area, I'm assuming this TV that you can't get picture on is in the garage area and there is a main TV in the living room that you are getting a picture on.
Generally all you need to do is hook a cable to the antenna hookup in the area of the TV, Turn the TV on, Set it to channel scan for OTA channels (Not Cable or SAT) and let it scan.
If you have done that and you are getting a picture on the main TV and not the Garage Area TV, I would look behind the main TV and see if the plate that has the antenna connection has a little light on it. This would be the booster and there is generally a very small button (Slightly bigger than the head of a pin) that you push in or out to activate the booster which is normally required when using OTA signals.
If the light is on, the booster is on.
If none of this has solved the issue, my next step would be to remove that wall plate with the booster on it and check to see if the coax connections are all solid. Generally the splitter is located either behind that booster plate or is part of the booster plate.
If that all checks out, remove the plate in the garage and check the connection there also.
If none of this works, The only other thing I can suggest at this point is to check the outside antenna hook up (if you have one) and see if that hookup produces a signal. If it does and you did not see a TRIPLE splitter, only a double when you checked behind the booster panel, I'm going to say they wired the wrong cable to the splitter.
If this is still under warranty, I'd try the above first and then haul it in to them if none of this gets you going.
2020 Chevrolet 2500 LTZ, 2019 Forest River Wolfpack 23Pack15, 2014 EZGO Golf Cart.