Best glue for attaching screen to phone?

My friend gave me his wife's old g2 that she dropped and shattered the digitizer. I bought a brand new pre assembled lcd/digitizer so all I'd have to do is use some 2mm tape and press it in to place. I'm now having an issue where from about the middle on the phone to the bottom is lifting around the edges. I thought I might have done a poor job with the tape so I went in and re did it 2 times now and still the same results. I'm wondering since the factory screen had this black glue like substance holding the screen in what can I use to mimic that and the results. I've read super glue was a bad idea because it gets between the LCD and digitizer. I also saw some one suggested gorilla glue epoxy (the 3300 psi stuff) I'm not worried with replacing the assembaly again in the event I drop my phone before I get a case. I'll just get the frame with the screen. Thanks in advance.