Having some troubles migrating Calendar items to Zimbra using this utility when migrating accounts other than my own:

"Could not retrieve base folder URL of Exchange Server. Appointments will not be imported. Either the permissions are not configured correctyly or because of Microsoft KB article 899351. Do you want to continue?"

Successful if:
1. I am logged on with my regular email account
2. I am migrating my own mailbox. No errors.

Not successful if:
1. Logged on with my Domain Admin account (with full mailbox access to ALL mailboxes)
2. email migrates just fine. Calendar items do not.

***Performed steps in KB article, using Domain Admin account with full mailbox perms***

Has anybody ran into this issue before and were you able to resolve?