True Bulletin, Listen Only, has the mailbox record not a greeting but an announcement.
The Caller App, default Bulletin Board, is designed to play announcement 1 only. That means that the mailbox you point the number to must have Announcement 1 recorded for the caller to hear the notice then hear good-bye and the hangup. If the mailbox has any other announcement recorded then the caller hears silence, followed by good-bye and then the hangup.
If you are creating a mailbox that will play more than one announcement then a more complex caller app will be needed.
Word of advice, Save the Sample App you are using to C:\Program Files|Avaya Modular Messaging\Caller Apps to what ever function you are creating. Meaning call the file something definitative for your application. In this way you won't have someone else modifying the file used under the Sample folder.