If you obtain a message with a message ID something other than ‘X00’, the message already exists in the message store. This will be the case with a message that has been saved to the work in progress folder. The ‘X00’ message ID is used for messages that are still being composed and do no yet exist in the message store.
I would probably need to see you applet to provide a definitive answer (you could email it to firstname.lastname@example.org). As a general rule, if you get a message ID other than ‘X00’, you can call GroupWise.Account.Refresh to ensure the API returns the most current version of your message. The message object also has a refresh method you can call to re-read the current values from the database.