You can wirelessly stream videos, music and photos from iPhone, iPad or iPod touch to Apple TV (2nd generation) and stream music to AirPlay speakers or receivers including AirPort Express using AirPlay. With AirPlay, you can also wirelessly stream videos and music from your computer to Apple TV (2nd generation) and stream music to AirPlay speakers or receivers including AirPort Express.
If Apple TV, Airport Express or compatible 3rd-party device does not appear in the AirPlay menu, follow these steps to resolve the issue:
1. Verify that AirPlay-enabled devices have the most up-to-date software or firmware.
2. Verify that all AirPlay-enabled devices are logged on to the same home Wi-Fi network.
3. Verify that iOS device has Wi-Fi turned on and is associated with the same home Wi-Fi network as AirPlay-enabled device.
4. Ensure that AirPlay is enabled on the device to which you are trying to stream content (for example, you can disable or enable AirPlay on Apple TV in the AirPlay menu: Settings > AirPlay).
5. Check Internet or network connectivity on all affected devices.
6. Temporarily disable firewalls (both network and local) and security software. Security software and firewalls may block ports that AirPlay uses to stream content. You can often resolve issues with security software by updating, correctly configuring or uninstalling security software.
7. Ensure that other devices are not trying to stream to the same AirPlay-enabled device at the same time.
8. Turn off Bluetooth on your iOS device by tapping Settings > General > Bluetooth.
9. If attempting to use AirPlay from a third-party app or a website from Safari app on iOS device, confirm that the app or website is AirPlay compatible.
via Apple Support