Did you put the plastic washer in between the tank and adapter?
Thank u i will have to try that. Anything special u used for greasing it up?I had this problem too, the paintball bottle's o-ring is too small.
I went to a home improvement store and they had different sized o-rings in the plumbing section, I used a #11 I think, it didn't work right away but after a few tries and greasing it up, it held air and has been holding for a month or so now no problem.