Most likely it's not you or your game, it's the site!
They're not giong to let you go up over that limit because there's to much of a chance you're going to withdraw some of your winnings.
I have the same problem at one of the site I play. I made the mistake of withdrawing half the money I had there. This was more then two YEARS ago and I never got over that half mark again.
I tryed all the games available at that site, Omaha, O8, stud, HE limit and NL, trnys and S&Gs and nothing works. My last experiment is with limit HE, over the first 30 sessions ( one session is one hour max. ), my record is 4 to 1 on the winning side. And over the next 30, my record drop to 1 to 4.
An this is just typical for how things go for my game. How could a player be doing that good for some time and then drop to being so bad over a four week period? The only reason I could see is that they don't wont to let me take more money out!
At least, they don't get me low enough to kick me out of the site!