Originally Posted by Bloodymurder
That is the over-pressurization protection valve. There is a small screw on the top or bottom of the reg near the operating pressure screw. Loosen that, and then turn the collar that surrounds the OP set screw, that will change the pressure at which the valve kicks in. Not sure which direction you have to turn it to make the desired change, but it won't be too hard to figure it out.
i tried that, but still not working.. what could it be?