gray "dead zones" after replacing screen

My iPod touch suffered a cracked screen, which I replaced thanks to the help this site provided. However, there seems to be an issue. If I open any app, I can see a series of small rectangular semi-translucent gray boxes on the screen, in something of a T formation across the width at the top, and along the length down the center. I have further discovered that these seem to be dead zones as far as touch controls are concerned, even though the display is showing.

Any thoughts as to what might be going on?