"JoeWayneRhea"Make sure gun is cocked .
Is not necessary with FX rifles as the hammer is floating, and not in contact with the valve stem.
Pretty likely there's something wrong with the valve itself. The Boss is however very easy to work on.
Remove barrel (3 screws on top of breech block)
Remove air bottle. (just unscrew it, it has a check valve)
Sometimes, it is also necessary to remove the interface in between the bottle and breech (the big hex "bolt")
Remove valve retainer (the black allen "nut" in between barrel and air interface)
After that, the valve can be taken out for inspection. Be careful not to loose the o-ring and valve spring behind the valve retainer.
Don't be afraid the valve spring will jump out or so while loosening the valve retainer, it won't happen