Q: Help needed, regarding my iMac, AirPlay and AppleTV

Hi, I'm trying to send wirelessly the content of my iMac to a device via my AppleTV (model A1469).

I've checked twice that my iMac and my AppleTV are connected to the same network, however

I cannot make the AirPlay work. The AirPlay status icon won't appear on the menu bar of my iMac

Can some one help, please?

Cheers.