you know your air source is good, sounds like your check valve may be gummed up and stuck.
If using a tank, I'd give it a hard blast and see if you can unstick it... otherwise, I'd empty, remove the check valve at the fill end and inspect the o ring. Since you would be removing it anyway, may be an ideal time to install a quick fill on it such as this one...
All those who believe in psychokinesis, raise my hand.
Good judgment comes from experience; experience usually comes from bad judgment.