I haven't been able to get it to scan anything either. Apparently the problem is the fixed focus camera being too blurry for anything except for jumbo codes, like those on shipping boxes. There's a reason it was $249... :-(
Out of milk is the only app that I found to work with the galaxy tab 2 until I tried the AT&T code scanner. I wish more scanners would work. Perhaps one that can use the rear camera could scan better.