Troubleshooting Step 1: Recharge Your iPad's Battery
If your iPad acts up in any way, shape, or form, the first thing you should try is to give its battery a full recharge before you proceed.
Don’t plug the iPad’s dock connector–to–USB cable into a USB port on your keyboard, monitor, or USB hub. You need to plug it into one of the USB ports on your computer itself. That’s because the USB ports on your computer supply more power than the other ports. Although other USB ports may do the trick, you’re better off using the built-in ones on your computer.
Most powered USB hubs, the kind you plug into an AC outlet, will charge your iPad just fine. But passive or unpowered hubs — ones that don’t plug into the wall for power — won’t cut it when it comes to charging your iPad.
If your computer is more than a few years old, even your built-in USB ports may not supply enough juice to recharge your iPad. It’ll sync just fine; it just won’t recharge. If it says Not Charging next to the battery icon at the top of the screen, use the included USB power adapter to recharge your iPad from an AC outlet rather than from a computer.
If you’re in a hurry, charge your iPad for a minimum of 20 minutes. A full charge is a better idea, but a charge of 20 or minutes is better than no charge at all. And for faster charging in any circumstances, turn off your iPad while it charges.