Night vision not working

I upgraded my cameras recently and the night vision does not work. It’s just a black screen. I adjusted the settings and nothing works. My old cameras worked fine. What’s the deal?? It’s very frustrating!!!

image|230x500

Upgraded as in replaced with the new outdoor type? If yes, are you using any previously purchased 3rd party mounts designed for the XT range? If yes, they cover the IR illuminator LED, rendering night vision useless.