Itouch will not charge? Or is it charging?

When I plug in my ipod to the all outlet, it shows a plug icon instead of a lightning bolt. It worked fine before, but now, it needs a charge, but rejects the charge. Sometimes, itll change to a lightning bolt, but then, itll switch back to a plug. Its at 20% battery, and it still rejects the charge.why?

Ipod 2nd Gen, newest software+Jailbroken

Charge: Ipod USB meant to be used with a USB AC adapter, and a Nikon Camera USB AC adapter

Added (1). No i tried it still doesn't work.

Mine does the same thing, try holding down the lock and home button for ten seconds. Then you can see if it works again, goodluck