Screen won’t work after I test it?

I have an iPhone 6 and I need to replace the screen. I put in my screen to test the phone and touch worked. I disconnected the display and assembled the screen and put it back in the phone. Touch no longer worked. I then ordered another screen and tested it. It worked. I did the same process and put the screen back on the phone. No touch. I tested the screen on other phones and it works fine. I’ve also tested other screens on the phone that I’m trying to fix and they work. Please help!