AudioBooks

I got my m6 mini so that i can listen to my books on tape.
Downloaded my first 2 and worked perfectly. Wonderful!
Went to download more and I get no sound, no play. Only the titles.
They are wmp format and the m6 mini is totally compatible. Any clue as to what is wrong. The resource is Overdrive. They told me to upgrade my firmware, but it is current. And besides, it worked oneday and not the next.
Help...

Do the ones that worked before still play?
If not, try to reinstall the firmware or even format the player once. Use the FAQ if you need help.

Yeah do what puffel said... if it doesn't help you can convert them to mp3... it also could that the files are to big... so maby splitting it in several files helps!