The following may be helpful in getting you calendars syncing correctly:
Specifically the section regarding syncing calendars:
For issues with syncing calendars
First, you should back up your calendars: Back up your calendars by choosing File > Export > Calendar Archive in OS X Mountain Lion or File > Export > iCal Archive in OS X Lion or Mac OS X v10.6. In Mac OS X v10.5, you can back up your iCal data by selecting File > Back up iCal.