If you think you misplaced something inside the tank, maybe look for a demo/review of the tank, one that shows unpackaging, the various components of the mod, etc., and what goes where. Could be as simple as a missing screw or O-ring, but I'm not familiar with that tank. Is there a reason particularly that you think you may have misplaced something? But if so, compare it to one that is being "demonstrated assembled" (do a youtube search, maybe) and see how yours compares.
However, like Brother Bob said, it could be many things causing the problem. But, if you feel you may have misplaced something or assembled it incorrectly, I might start there first, to see if it's something simple but necessary, as it were....
Good luck, I imagine with enough time and patience, you'll find the solution. Good luck!
Anna