How far are you shooting? The barrel is about 1 1/2" below the scope. Most scopes are 1/4" per click at 100 yards. At twenty yards this translates to 20 clicks to move 1". If you are at ten yards, the group should be about 1" or so low. If you are at twenty yards, the group can be centered, but if you go 1" high at twenty, it will be close to zero at forty. There could also be some droop. This can be compensated for by a drooper mount, or my preferred method, bending the barrel. There are several tutorials in the library.
I had a large amount of barrel droop on my NP2 model sold at Big 5. I could have returned it, but I got the last one. I have a raccoon problem that is out of control, so I didn't want to wait. I removed the barrel shroud and used a forked tree to bend the barrel. It sounds very crude, but it works amazing well. I went slowly and got it very close to zero, with several iterations. I was surprised by how little force it took to tweak the barrel with the tree. I tried building a barrel bending fixture shown in this forum, but it wasn't working for me.The goal is get close to zero in the middle of the scope adjustments, by bending the barrel. Don't adjust your scope until it's close to the end of it's limits. It will not hold zero.After getting the barrel adjusted, then zeroing it in with a few clicks, I was ready. Two raccoons in two nights, so far. This pellet gun is great, once you spend some time getting it dialed in. It's a lot of bang for the buck. The last thing I need to do is work on the trigger.