If the disabled iPad has never been synced to iTunes on the computer. When you plug in your disabled device to a computer you have previously synced to, ensure that you sync the device again before you try to unlock your disabled iPad.
You should always backup all your mobile devices from time to time as unlocking a disabled iPad will erase all the existing personal files and data on the device. Remember to Back up your iPad if Possible How Can I Unlock Disabled iPad in Recovery Mode? How to Unlock Disabled iPad with iTunes Directly?
