Currently Being ModeratedAug 1, 2013 7:23 AM (in response to Calypso2012)
Welcome to Apple Support Communities, and thanks for the question. I would check out this article and see if that resolves the issue. It'll go over troubleshooting steps for iCloud Calendar:
Alternatively, if you're syncing using iTunes instead of using iCloud Calendar, you can check this next one out. Before doing that though, you'll want to follow the first two steps it goes over, including resetting sync history.
All the best,