SideCar won't operate! Are my models not compatible?

Hi,

I can't get SideCar to operate between my devices. I got my iMac just a month ago and my iPad about a year ago, I thought recent models were all compatible for SideCar.. but maybe not? I'm not sure why it won't work, I've tried so many times to get them to connect but theres no sign of hope :(

I have an iMac (Retina 4K, 21.5-inch, 2019) and an iPad Pro (10.5-inch, 2017).

Please help! Thank you