UIButton not responding after set frame within UIScrollview

I have a UIScrollView which content is designed with Interface Builder. It has a table with a UIButton below. If the button wasn't moved before, it works (touchesBegan and TouchUpInside get called), but if it was moved using 'button.frame = ' in response of content growth (the table got bigger), it stops responding to any touch.

I verified that there's no hidden view in front of it, I even used bringViewToFront.