Hi Welcome to JustAnswer
Did you check if the problem is in Ipad or charger by using other charger ?
In some cases it shows charging symbol but it does not charge. In your case as well is such thing happening ?
Force restart your device: Press and hold the Sleep/Wake and Home buttons at the same time for at least 10 seconds, until you see the Apple logo. Then let your device charge for another half hour.
Try this and let me know how it goes
Did this work ?