Your iPad may lock (and display a message that it is locked) if you enter the wrong passcode or PIN a few times. Usually the lock will clear in a little while by itself.

However, if you enter the wrong passcode 6 or more times, your iPad will display iPad Disabled and permanently lock. In that case:

1. Follow the instructions in this link to restore your iPad.
2. Then, run the iPad setup process and be sure to choose Restore from iCloudBackup on the Setup Up iPad screen.
3. After the Apple setup is complete, enroll your iPad for D-E resources by using Safari on the iPad to go to http://bit.ly/casperenroll
4.  Login with your D-E username (no @d-e.org) and My DE password.
5. Answer, Install, Yes, or OK to all the prompts.  You are enrolled when you get to the last screen that says enrollment verified.

Note that the process above will result in you loosing all data created or changed since the last time the iCloud ran on your computer.