The most common error is not conditioning the 510 batts right out of the box. First charge is 8 hrs....30 minutes of vaping....and then another hr of charging. I don't know why these batts are different from the 401s, 801s, 901s etc etc....but they are. Incorrect conditioning can lead to a poor draw and vapor production right off the bat (no pun intended).
Several other causes that I should mention are quite simple. I've noticed several factory carts that the stuffing is over-packed. If you can't get a good draw when simply drawing on the cart all by itself, you won't get a good draw when it's hooked up to the batt. Another simple fault could be even easier than restuffing a cart. If anything gets in one of the intake holes - a piece of dust, a piece of lint...anything at all, it won't draw correctly. Plug the batt side of the atom with your pinkie and blow thru the cart side. You should feel two columns of air blowing easily out either side near the threads. Even a little dried liquid or gunk from an overfill can cause this.
I assume you tried both atoms that came with the kit. If it's not the atom, then it would have to be either the batt or the cart. There is simply nothing else to keep you from experiencing what we all know. The 510
rocks!
I hope that helps, good luck, and welcome to the group!