IPad Not charging? WHAT A BUNCH OF DIARRHEA, HELPPPPP?

Hey guys my I own a mac and an iPad and recently when ever I connect my iPad to the mac the iPad syncs but I will not charge, like it will say on the iPad "Not Charging" I know it sounds like a steamy plate of diarrhea but trust it does, the iPad was gotten last christmas so its the old version, I mean right now it says not charging, so can any one help he with this. Thanks guys