Smart cover not working on new iPad

After I restore my new iPad 4G from my 1st gen iPad's backup, the smart cover is nott working. I go to Settings > General, there is no "iPad Cover Lock/Unlock" option. Do a reset can't fix the issue.First Activate the sleep/wake option in settings. Then reposition the lid so its a couple of centimetres higher up. The new iPad will detect the Smart Cover and that option can be found.