Black Glowing Screen But No Image?

My sister recently broke the glass on her Verizon iPhone 4 and since I've already changed my display assembly on my AT&T iPhone 4 she asked if I could change hers. I agreed to and started the job this past Thursday. Thursday night I took it apart and got up Friday and put it back together with the new assembly. Upon finishing the assembly the phone powers on and the backlight kicks on with all regular functions (phone calls, text, pushing power or home button, etc...) but there's no image on the LCD. It just stays black. I did the hard reset off of her computer (that was tricky since nothing shows on the screen at all but I got it) and it didn't fix anything. I then disconnected the new display assembly and reconnected the old assembly and now the old assembly is doing the same thing. Back light works great but the LCD doesn't do anything. Suggestions?