How do I zero a NC-RD-DDAB?

If you have loosened the rear locking screws and have the sight mounted where you want it, adjust the dot up or down until boresighted or zeroed. Then lock the lock screws back down. You say it's attached to a scope? If so it may be the mount that is around the scope tube causing you problems. Try turning it around and see if it makes a difference. I have one of these and it works fine.

I've read the comments on the subject sight and almost all of them call this item a piece of garbage in so many words. However, one of the comments indicated that the user was able to get it to work, so I haven't quite given up hope on it just yet. The basic problem I'm having is one of elevation--even when adjusted to the limit of the "up" elevation adjustment, the rifle still fires low (by at least a couple of feet at 50 yards). This was consistent with what I expected before I started shooting after I compared the red dot with the telescopic sight it's attached to. I fired a few rounds, just to confirm that, then quit.

I suspect that if there is any hope in getting this sight to work, it probably lies with understanding how it should be adjusted. The complete lack of basic instructions on how to go about zeroing and what the set screws (in particular) do is at best irresponsible on the part of NcStar.

So, is there a way to get the DDAB grossly adjusted to the point where fine adjustments can be made with the "up" an "R" screws? Or should I just save my ammo, toss it, and not buy any more NcStar products?