There are many things you have to be aware of: you must have proper gluing AND a perfect fit.
- Most important is to avoid compressing the folded digitizer cable, which will damage it and may cause the digitizer to become non-responsive, or cause ghost-typing (works alone).
- Clean the iPad (the aluminum side) very well with isopropyl alcohol (85%+) or goo-off to remove the old glue. Don't do so with the digitizer which is delicate and may be scratched or damaged.
- Check that everything is working properly (lcd, WiFi, front and back camera, volume up/down, mute, power) before regluing the digitizer. And check that the LCD and inside of the digitizer are clean. Use a dry lens clothe to clean any smudges or fingerprints.
- Get double-sided tape: http://www.amazon.com/Tesa-Double-sided-...
- Apply the double tape to the aluminum frame (cut it to fit, of course).
- When re-gluing the digitizer, first fit in place the right-side of the digitizer and iPad, opposite of where the digitizer cable is located. Then gradually move to the left side, while using a spudger or plastic opening tool to carefully push the digitizer flat cable in the pre-cut "hole/gap," gradually as you "close" the iPad. The idea is to keep the flat cable from getting caught and sandwiched between the frame and and the digitizer glass.
If you do it properly, the flat cable will not be compressed right underneath the glass, causing it to pop out of place, and most important will avoid damage to the flat cable itself.