I have a tendency to clean my Tippmann A-5 after every game I play.  And when I say clean, I mean take it apart and give it a good wipe.  So this past weekend, I took my A-5 apart, cleaned it, and put it back together.  Right after I cleaned it, I screwed in the CO2 to make sure it is set to go for the next game I play.  As I screw it in, the air begins to leak from the valve thats connected to the tombstone, a major leak.  So at first thought, maybe the o-ring broke.  So I replaced it, and still the same leak.  I oiled it, and still the same leak.  Replaced the o-ring 3 times, and still the same annoying leak. 

It worked perfectly the last game I played.  I'm stumped, any ideas?