Close active file without closing other Excel files

[legg]

I have a set of spreadsheets that are open simultaneously. All use the same special menu with normal Excel menus disabled. Any attempt to close one file makes Excel close them all no matter what file close command I put in the close subroutine:

Sub RTClose()
ActiveWorkbook.Close SaveChanges:=False
End Sub

I have tried:
ActiveWorkbook.Close
ThisWorkbook.Close
Workbooks("Filename").Close
Even changing the file close subroutine name so it cannot be confused has no effect.
Can anyone help?