What service is your calendar synced with?
Make sure you have your calendar set to sync with your account. If you are not syncing with some service; iCloud, Google, Yahoo, etc., then the Sync setting would be irrelevant, and probably not show. Apple tends to hide settings if they are not relevant.
If your account does have Calendar syncing turned on, try turning it off, visit the Calendar app to make sure it is off, then turning it back on.
If you've never turned on Calendar syncing before, make sure you Keep your events on the iPad when doing this.
If you've been syncing with your account, visit the website and make sure all your events are there, then chose to delete the local calendar events when turning it off. This will be cleaner than keeping them, which might result in duplicates when you turn syncing back on; though it should not.