Restart the computer. Restart the iPad.
On the iPad: Hold down the power button until the power off slider appears. Slide it off. When the iPad finishes shutting down, hold down the power button again until the Apple logo appears.
Try again. That's the only thing I can think of at the moment.
In the long term I suggest syncing both Outlook and the iPad online. Both can be set up to sync with Google Calendars.
The benefits are: Instant (as long as you have internet) syncing between the devices. You no longer need to worry about conflicts because you changed the same item on both devices. You have an online backup incase something goes wrong with your computer and iPad. The ability to get to and change your calendars from any computer with internet access and a browser.
To get the most out of Google and the iPad, set it up as an Exchange account. This allows you to sync your contacts and multiple calendars; two things you can not do with the standard GMail account setup.
Setting up Google Sync with your iOS device : Google Sync (ActiveSync) - Google Mobile Help
You don't have to actually use the mail account if you don't want to, but an extra email account also comes in handy at times.
