Is there anything wrong with the passcode? If your iPad is locked and you forget the passcode, please follow the steps below to unlock it.
1.Connect your iPad to your PC or Mac.
2.Select your device in the iTunes sidebar, and click the"Summary" tab.
3.Click "Check for Update". iTunes will show you if there any new version of iPad software is available.
4.Click "Restore iPad". You can finish the restore process by following the instructions given. During the process, a recommend that tells you to back up your files will be given. You can restore your data after the process is complete.
Now, you must have restored your iPad.
Note: Even you bring your iPad to the Apple service center, Apple staff also need to restore your iPad to unlock it. That's to say, you need to erase everything on it.