Why is my digitizer freaking out?

Hello! I recently purchased an iPad for repair purposes. Unbeknownst to me, it was an EMC 2560 model. I'm still waiting for a response from the seller but in the meantime, I stuck a 2415 white digitizer I had lying around on it. Now it's freaking out. As I'm writing this I am in a constant battle trying to type legibly. It seems to Szvxbzv. There. You. Egg go. Right then it malfunctioned. It randomly types keys, and registers random signals. I'm not sure what the problem is, is it my digitizer or the fact that I put a 2415 on a 2560 logic board? Or neither? Thanks!