Replacing glass only now display is so faint I can barely see it.

I'm having my first try at replacing just the glass on the iPhone 5 display.

I have a fair few smashed screens lying around and I've bought a few bits and bobs I will need ready to give it a try.

The first screen I ruined as I gave it too much heat and fried it. The second seemed to be going ok till I tested it just now.

I am at the stage where I have removed the frame and the glass leaving me with the digitiser and the backlight. When I plug it into the phone, it turns on, backlight is working but I can see anything unless I hold it at a certain angle then I can just about make out whats supposed to be on the display.

Does anybody know where I went wrong? I have a feeling I peeled off a layer of something I shouldn't have along with the glue.