won't keep a charge

Hi- my shuffle either isn't charging correctly or won't hold a charge. I hook it up with the usb to my computer and it blinks orange so I hit "Eject" and the light stays steady green. I leave it plugged into the computer and take it off after 8 hrs or overnight. When I turn it on to check the charge, the light is green and music plays, so I turn it off. But when I go to use it later (like 2- 6 hours), nothing happens. No light, no music, nothing. Help! Is it something I'm doing wrong while charging? I don't have itunes loaded on my work or home computer- could that be it? I've charged it on both computers before and it worked. I've only had it about 2 months...