Screen replaced now digitizer is not working.

Hi,

I have a friend who cracked the screen on her 4th gen iPod Touch 32GB. I bought a front assembly from eBay and followed the guide on here for replacing it. When I installed the new one it comes on and looks fine but I can't use the touch screen. At first the bottom 2 rows worked but not the top rows. I unattached and reconnected my ribbons and then had the same issue. I've tried resetting it back to factory with no resolution. I attached the old back up and the digitizer works and I can use the ipod except for the broken screen. When I went back to the new assembly now I can't even get the bottom row to work. It will not allow any interaction with the touch screen.

I'm an IT guy and this is my 1st iPod repair but I've done lots of repair projects before and I'm fairly certain I haven't damaged any of the components. Should I try to return the assembly for a new one or is there something else I can try to fix the problem?

thanks