Sounds like the full flow safety valve has been tripped. Some times called a line burst valve , it's a safety built into the tank shut off and can be triggered by opening the supply valve too quickly. Turn the supply valve on the tank off, make sure all propane appliances are off, and open the valve very slowly, back pressure in the system keeps the valve open. Then retest all you appliances.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.