I cannot unplug my iPod nano from iTunes because it says I have more devices using my archives but I don´t have any. I even cannot restore it.

My iPod nano have the windows format. I bought a mac and now when I connect with iTunes (from mac) it says I can´t update and restore because I have more devices using my archives. I cancel authorization from other devices but still keep saying the same msj.

Please I need a solution to restore (Windows to Mac) my iPod and unplug with no problems.