It could be both...
I would start by doing a thorough visual inspection of the digitizer connectors on the logic board to insure there isn't any debris. The digitizer connectors also have locking flaps; check them to insure they are not cracked or broken which could cause improper electrical connections. Finally, inspect the flex for tears. Even micro-tears can be problematic due to the trace density involved.
If all of that looks okay, then it's probably your digitizer. You could order another one and try again or have the one you ordered replaced under warranty.