fm radio doesn't play

For my iPod Nano 5th generation, the FM tuner will not play any more.

--> I can select the tuner

--> When I turn the volume wheel, I do hear the clicks ==> I just don't hear the music

--> Changing the station doesn't help
(Yes, headphones are plugged in. Without headphones, I still get the menu display that informs me that the headphones are the required FM tuner antenna)

I also did a complete factory reset through iTunes and this still didn't solve the problem.

Has anyone else heard of this issue before?

Thanks!