airplay mirroring icon missing iMac purchased 2013

Hi, Nuria OMahony.

Thank you for visiting Apple Support Communities.

Here are a couple article that I would recommend going through when experiencing issues with AirPlay.

Troubleshooting AirPlay Mirroring

Mac and Apple TV are on the same network, but no AirPlay Mirroring menu appears

Your Apple TV may be asleep. Simply press a button on your Apple TV remote to wake it up. After a few seconds, the AirPlay Mirroring menu extra will appear.

Make sure your Apple TV has the current software update installed.

Make sure you have the "Show mirroring options in the menu bar when available" checked.

The menu bar or Dock is cropped in Mountain Lion

Some HDTVs have bezels that cover a small percentage of the screen. This will result in a slight cropping of a full-resolution HDTV image. Depending on the HDTV model, AirPlay Mirroring may automatically adjust the picture size to prevent cropping. If you see cropping of the menu bar or dock on your HDTV when using AirPlay Mirroring, simply click the Overscan correction option in Displays preferences.

Firewall security settings

If you use the firewall, make sure the following firewall security options have been set to allow AirPlay Mirroring to work:

1. Choose Apple menu () > System Preferences.
2. Click Security & Privacy, and then click Firewall.
3. Click the lock icon to unlock it if it's locked, then type an administrator name and password.
4. Click Firewall Options.
5. Uncheck (deselect) “Block all incoming connections” checkbox.
6. Select (check) the “Automatically allow signed software to receive incoming connections” checkbox.

About AirPlay Mirroring in OS X

http://support.apple.com/kb/ht5404

iTunes: Troubleshooting AirPlay and AirPlay Mirroring

http://support.apple.com/kb/TS5209

Cheers,

Jason H.