If your iPad is not charging, the most likely cause is that your computer USB port isn’t offering enough power because iPads need a lot more energy than other Apple devices in order to charge properly. The best thing to do is to plug the charger into your wall outlet and allow the iPad to charge that way. Or, you can try putting the iPad into suspend mode and see if it will charge through your computer in this way. If you don’t see the lightning bolt on the screen though, or “Not Charging”, then you will know that your device still isn’t charging.

If your iPad is not charging even if you plug it into a wall outlet, try rebooting it by holding down the suspend button. After it has shut down completely and allowed to rest for a minute, hold the suspend button down again until you see the Apple logo notifying you the device is booting back up. Then try to charge it through the wall outlet again.

If rebooting your iPad doesn’t work to make it start charging, then you need to check your adaptor and cable to make sure those are working. If the charging problem is because of the adaptor or cable going bad, then you will need to replace those and then your iPad should begin to charge. If that still doesn’t work, there may be hardware problem that needs to be repaired.

Source About iPad