I play pump. There was a thread on paintball montreal a while ago for interested players: Paintball Montreal :: Voir le sujet - Du monde joue au pompe??
(I'm Surestick there as well BTW)
I have some friends who've had trouble registering there too, I don't remember if it was the "click here to activate your account" email going to the junk folder or the admins taking forever to approve new members. Try a few different email addresses maybe?
If you really have trouble PM me & I'll try to PM one of the admins or something asking why you can't register.