Could it be that the game is scaled for the iPhone 5 display, with a small region at the top and bottom of black to maintain proportions? If so, then touching them may be having the same effect as removing your finger from the screen.
Don't quite follow you Nocturne. width=640; height=1136; The game is scaling up and down for ipad and iphone4 only. Controls work fine on them though. I'm starting to think it may be an iphone5 hardware or software error. ????