There’s an easy way to find out whether your Mac supports AirPlay Mirroring: If you see AirPlay Display (Mavericks) or AirPlay Mirroring (Mountain Lion) options in the Displays pane of System Preferences, then your Mac model supports it. If you don’t see it, this feature isn’t supported.
There are some things to consider:
- Your Mac and Apple TV have to be on the same network.
- Check also that your Apple TV isn’t asleep (wake it up by pressing a button on the Apple Remote and wait some seconds).
- Be sure that the “Show mirroring options in the menu bar when available” option in the Displays pane of System Preferences is selected