Why Will My iPod touch Only Charge On My Computer?

I got a iPod touch 1st gen last year. I havent had ANY problems with it until now. It will no longer charge on my sisters docking station, nor will it charge on my charger which I plug into the wall. Sometimes when I try to charge it, either nothing happens or it will show the symbol for it being fully charged, when its not fully charged. Anyone know how to fix this problem, or why this is happening? By the way its been doing this for about a week or so.