Hi, i had a similar problem but its fixed now. you need to make sure the rubber isn't pushed down all the way. when it is just fixed in the plastic bit of the valve, turn it slowly until the bubbles start. if you look there is a spiral on the rubber bit of the valve and a "notch" cut in the plastic bit of the valve. you should turn it until a bit of spiral is visible in the notch/ above the notch if that makes sense. i would demonstrate but thats not easily possible.