Your problem is likely the overflow protection device on the tank, known as the OPD. Try this simple fix: close the valve on the tank, wait a few minutes and the open the valve slowly, slowly being the important part. Open a burner control on your stove and light. It might take a few seconds for the gas to reach the burner. Costs you nothing to try, so go for it.
Happy Camping! ///// Richard D.
2006 4x4 Ford 250 SD / 2007 Flagstaff 827 FLS
One very patient wife and one furry child who travels with us. Forty-two years of trailering and camping, and I still have a blast.