My iPod won't eject?

Hey,

There is probably a really simple answer to this, but I havent really used itunes before so I have no idea. Basically, I imported a CD into my laptop and then synced my ipod. As I clicked the eject logo, a message popped up saying: 'The ipod (Katy's ipod) cannot be ejected because it contains files that are in use by another application'. No matter how many times I restart my programme or put the wire back into my computer with the ipod, it just won't work. Any tips on how to safely eject my ipod with my music on it and get this message to go away?

Thank you in advance 🙂