Classic V4 - Message button is missing in BlueNote Actions

When you open the BlueNote Action window for each Location on the NoteBoard, there needs to be at least one user who has selected that Location in order for the Message button to appear.

Here's an example of how to get a Message button to appear within BlueNote Actions:

Go to the computer in Op 1, and within the BlueNote client software on that computer, choose Menu > User and Location. Under Location Settings, scroll down and choose Op 1, then check the box that says "Include this location in the  recipients  list for Typed messages."

Repeat this for all the locations where you wish to have the message button reappear. You'll notice that the chevrons at each NoteBoard location that have locations set will change from black to white.