IPhone 4 screen problem

[clifflee33]

Ok so I recently cracked the screen on my iPhone 4, and, being short on money, thought I could replace the screen myself. I bought a replacement screen from a retailer and did everything right (so I think), and replaced it myself. However, while the phone charges, vibrates, and rings when I receive calls, the screen shows nothing but a dim background light. I tried putting my old screen in and the same result happens. Can anyone help me think of something I might be doing wrong or provide anything I need to do in order to fix this?