[aiharkness]

You will not see a choice named default in the drop down, just the email addresses that you have installed in BIS (I'm assuming we are talking strictly BIS, and not BES).

Desktop Manager will sync the calendar that is selected as the default CICAL in default services. (Set the default CMIME to the same address.)

If, on the otherhand, you have other email addresses in BIS and still only see the gmail address, that's a different story. Do a hard reset (battery pull with the power on, and wait at least 30 seconds before reinstalling the battery). If that doesn't fix it, resend service books.