Why can't I play the audio files in the Klett Sprachen App? 25 June 2021 12:47 Updated The volume might be turned off. Check to make sure the loudspeaker volume is on. Related articles Can I play media files in the Klett Sprachen App? Why is the Klett Sprachen App not working? How can I play the audios for my book in allango? Why is the menu control bar not visible in the Klett Spachen App? Where can I find the licence key for my product?