Why doesn't the touch screen respond after repair?

I got a replacement screen for my HTC EVO LTE and I replaced it. It comes on, the screen lights up as it should, but it does not respond to touch. So after trouble shooting it for awhile, I discovered that after screwing in the top right screw (Phone facing down and back panel is exposed) the touch screen does not respond. but if I unscrew it and there is nothing holding down the motherboard in that section, the touch screen works. Can anyone explain what is going on and how to fix it so I can put in all the screws and the rear panel.