replacement screen doesnt work just black

i have replaced my verizon iphone 4 screen w/ a new one. i was very exact and careful when i did the procedure.turned it on and the screen doesnt work.now, the phone is on because i can play music, i can even swipe to turn off phone. but i cant see anything.i did search forums here, and i tried plugging phone into computer and even restoring it but to no resolve.i just bought a second screen and tried it, again being extremely careful w/ the teardown, and i have the same problem with the second screen.i'm pretty new to this particular device so i dont know where to go from here. thank you all for any help and advice.