New Trackpad Won't Pair with Mac Mini

I just picked up a brand new magic trackpad, plugged it into my mac mini using the supplied lightning cable, and.... nothing. It doesn't pair. At the same time, I bought a brand new Magic Keyboard, plugged it in, and it works fine. It's just the trackpad that won't work.

The Mac Mini never had any wireless items paired to it. Bluetooth is on. The green switch on the trackpad is on.

Any help would be greatly appreciated. Quite a shame a brand new, out of the box item can't even pair properly.