Hi Don Wise,
OK, I see the issue if you have the word "Department" highlighted when you right mouse click. If you have any department selected, then the OK button will be enabled as soon as you type your first question mark ("?"). A bit disconcerting.
In any event, just add a single department into the Ledger (Edit | Departments) to give yourself something to click on. The department doesn't have to exist.
How can you be creating departmental masks with no departments? I don't think I understand that.