I need help iphone 3G screen replacement

I replaced the screen and digitizer, when put back together the screen doesn't respond to touch (turns on and goes to the unlock screen). Any help on what to do next??

thanks

[quote|carmikenc]I replaced the screen and digitizer, when put back together the screen doesn't respond to touch (turns on and goes to the unlock screen). Any help on what to do next?? thanks[/quote]