Digitizer stops working after 20 min.

Hello,

I've got an iPad 2 digitizer that I've replaced on this iPad 2. Everything works fine initially. It is when it is in use for about 20 minutes or so, the digitizer become partly unresponsive. This means that only some areas work.

Anyone who can tell me what the problem could be and what I could do to solve this?

I've already set it back to the factory defaults.

Thanks!