When you connect the cable to your laptop does it say "Not Charging"? If so, that indicates that the cable is good. Plus, it will charge, but slowly. Then it's most likely the wall charger.
Try this - Reset the iPad by holding down on the Sleep and Home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider - let go of the buttons. (This is equivalent to rebooting your computer.)