So, picked up a new trackpad. It connects fine to my iMac (late 2012) but it is not detected in System Preferences as a trackpad. I can move the cursor but I cannot scroll, zoom or swipe with it. I have OS X El Capitan and have rebooted, checked for updates, unpaired and re-paired, tried via wired connection with lightning. Nothing gets it going. I did have the previous version of the trackpad but that is no longer operational and have been using the magic mouse for the past 6 months or so. The mouse works fine for gestures.