I don't know if this will help but I he the same problem when I fixed my digitizer and my only thought was to fold a piece of tape over and double it up so it had more holding area. Maybe the cable is pushing up on the digitizer and it just needs a little more adhesive to fill the gap. Anyway, it took care of my iPad which had sections not sticking. In fact I double all my tape and now it's nice and tight ..
If you have fixed a lot of iPads, any idea why the extreme left side of my digitizer might not be working?( see my post)
Thanks!