Glass keeps popping up on side of home button.

After I complete a iPad 3 repair the glass never stays where it's suppose to stay. In other words it begins to separate from frame.

Here's what I do before I place adhesive down.

Remove bezel clean all old glue from under bezel. Remove all old digitizer glue from around frame. Scrapping with a plastic tool then I use alcohol pads to remove any remaining glue from old tape. I place new tape in bezel slot and peel the back off then place new bezel on, pressing it into place with a tool. Then I peel off back of the already installed tape on new digitizer, this pre installed tape on underside of digitizer glass is a great idea by the way. I push glass into place pressing all along the outer edge of iPad. I then heat up edge to get glue nice and sticky and finally secure the edges with small wood clamps to hold it in place. The next day, about 24 hours later I remove the clamps. By the next day or so the glass begins to seperate, usually around home button side. Any ideas on how to make a perfect seal?

Thank you

Dave