I've put together more furniture than I like to admit, so I'm accustomed to sometimes running into challenges.  This purchase was one of those.  One of the frame sections was drilled completely backward so the shelf would not screw in unless that frame section was reversed.  Not a big problem, but it does  mean that the frame section is not screwed into the rest of the frame. Fortunately, it was one of the middle metal frame sections so it's secured by the weight of the shelves.    

Pros: Good value
Cons: Frame holes drilled backward.