Replaced iPhone 5c screen, but now has one white vertical line

This is the second screen I've replaced. The first one worked beautifully. I ordered another from the same place on amazon.com for my son's phone and now I see one white vertical line down the middle of the phone. The old screen was broken, but I've tried reconnecting it and although it looks okay, it still has some lines, etc. So now I'm really thrown on finding a solution because both screens technically don't work. Help!