I've recently bought Balliihoo caps for my barrels and the 'control cap top up tap', to add gas. However, when I connect this 'control cap top up tap' to the cap's inlet valve, no gas goes into the barrel. The cap's inlet valve does works - I've tried it with the car foot pump. But it seems that 'control cap top up tap' isn't depressing the button in the inlet valve that allows gas to enter the barrel. Has anyone else had this problem? Thanks