there are 4 main things that stop co2.
the co2 on/off valve on the co2 tank,
the pressure valve (the adjusting knob thingy on the main regulator, should have the co2 art logo written on) this adjusts the working pressure inside the regulator,
the solenoid needs to be plugged in to allow co2 through,
lastly bubble counter. with this one you can fine tune how much co2 you are outting out.
check all 4 are on and you should be good to go.