This sounds like it may be a hardware problem with the Lightning or Dock connector.
Try a hard reboot first>
Once your iPad has rebooted, try plugging it in again. If it starts to charge, you're good. If that fails try this next please>
Please reply and let me know if you need any other assistance or if everything is good, take a moment to rate my service by choosing one of the stars at the top, then click submit.
Thank you very much!
If that doesnt work you can try the following steps