Have you tried copying all Outlook Calendar items from one folder to another? What is the result that you got?
In Microsoft Office Outlook 2007, Outlook 2003, Outlook 2002, and Outlook 2000, you cannot copy all the items in a Calendar folder when you right-click the folder, you click Copy Calendar, and then you paste in another top-level folder. Instead, this method creates a new subfolder under the destination folder.
To copy all of the items from a Calendar folder to another folder, you must select each item and then copy and paste it to the target folder.
Please refer the KB, so that you can get some alternate ways to do this.