water hooked up, turned on, but not flowing inside!

I just bought a 1968 Ambassador. I hooked up the hose the valve at the rear of the trailer and turned on the water. No water will flow inside the trailer. I've tried everything, thinking there must be a valve that was shut off, but can't get it working! So frustrating! There are two valves in back (red circular faucet handles) and these do nothing. I can't find anything under the sink in the bathroom (rear bathroom)

Any ideas on what could be blocking the water?

Please help!

Thanks,

Jim