Can move icons around on screen, but can't press any buttons

This is a bizarre problem to have.

Did a screen replacement, using an OEM screen. Didn't have any problems with the repair and I checked all functionality before gluing it shut; there weren't any issues. However, now - as I'm trying to use it - the top of the screen (an area about 1.5" by 4", top left corner) won't let me push any buttons. I can move icons around in the affected area, but I can't press anything (like the "back" button in the Facebook app, for example). Why would the digitizer do that?? And is there anyway to fix this??