How much psi do you have in the tank?
Will that tank pressurize another marker?
It could be the valve pin in the reg not fully opening.
Next I'd disconnect the gas line near where the tank screws in to see if the asa will blow air through there. Some on/off don't work properly. Then reconnect there and disconnect on the regulator side to see if air will come through there. Clogged macro rarely happens but it does happen. Then reconnect and take the reg off, feel if air comes out the top of the reg. Maybe its set way too low, virtually off. This will at least get you up to the gauge. What does that gauge read when no gas is connected?
My gearbag has wheels on it, not because its heavy, its just ready to roll any weekend.