Oring by valve keeps coming out of 4500 psi tank! Help.

I have a 4500 psi interspiro carbon fiber tank. I bought a new valve from airhog and had it hydro tested. The safety place put the valve on it for me and when I filled the tank all was well. The next morning I was gonna go shoot my new bobcat 30 went to fill it for the first time. NO AIR. The tank was empty! I noticed the oring under the valve was bulged out of the joint causing the leak. Bummer! Put in a new Oring filled tank again SAME THING. Can anyone help with some advice on my dilemma? I cant get ahold of airhog I keep getting a recording and no call back, seems they are really busy.