Recording playback not working

Due to a broken charger on my MacBook Pro I am obliged to use my iPad for a couple of days but when I came to use the recording and playback feature of Devonthink To Go I found that it would not playback an recording either made directly into the app or imported. All that happens is that when I press the playback button it flashes and that’s it, no movement on the slider at all. Am I doing something wrong or is there a problem here? Thanks for any help.