I cant' get a flow of gas through the regulator.

I cant' get a flow of gas through the regulator. Full tank of gas, plenty of spark. I can usually hear the gas flow when opening one of the three valves up top to light. So there is definitely no flow. I tried the "turn on the tank and wait for one minute" theory to no avail. The problem has steadily gotten worse over the course of one-and-a-half years I've had the grill. Usually I can unhook the line from the tank and hook it back up that starts the flow again. Now, even that doesn't work.

Please help...
Rick