screen won't stay stuck

I am having trouble with HTC smartphone repairs. I have tried fixing two Trophys, an HD7, an One X, and a Thunderbolt. On all of these, I have a problem with the digitizer not adhering properly ant the bottom of the screen. They just don't want to stick to the frame good. I have tried the 3M adhesive sheets, as well as a roll of 2mm adhesive. I have heated the frame before putting the adhesive down, as well as letting it sit overnight with clothespins keeping pressure.

Any suggestions?

Also, I have noticed that the original adhesive is a lot thicker and kind-of spongy. anywhere to get adhesive that is equal to that used by the manufacture?