Originally Posted by -=£em in Pa=-
Before you screw the adaptor on, tap the unscrewed valve on the tube few times releasing some air . This should help
bingo
The little pin gets stuck and you can't get it to release w/ pressure. Jerk it around a bit to help that.
Also, don't be shy with the pump. It will never push air in with the first stroke if the tube is semi-pumped already when you go at it. You have to build up pressure in the pump's nozzle tube to make it move the valve. On my floor pump w/ a long rubber tube that easily takes 5-6 strokes.