my mac do not see my ipod shuffle 2nd generation

Hi, I need help. my mac (10.7.4) can not see my ipod shuffle 2nd generation. ipod does not appear either on the desktop or in itunes. I tried to look into the information system under usb but also nothing. Then I try to get my ipod to another computer (iMac G4 flat panel (10.5.8)) but again nothing. only shows that is charging. Even a week ago I sync it with iTunes and then to work.

Please help me! :))))