Please turn off the iPad / iPhone completely. Hold down the power button for more than 10 seconds, and wait until the power-off bar shows up. Shut down the device, and after 10 seconds, reboot again. Now try again to play KinderApp.
If it still doesn't work, please do the following:
• Check if your ringtone is turned on and the volume is up.
• Turn off Airplay. Make sure that the sound is not being transmitted to a remote speaker via Airplay.
• Have you installed the latest version of iOS? Minimum requirement is iOS 8. Please update if you have an older version.
• The latest versions of KinderApp, please update if you are running an older version.