I've seen issues with this all the way back to 2003. The problem is that your Calendar is a local file and is tied to the first email account you placed in outlook. If your IMAP has a calendar on the web, you need to link that to the mailbox for the IMAP account. In other words, you need to set it up as a separate PST. THe only other question I have for you is: Did you Set up IMAP first?