How to make this deselect box code work

[Pauljj]

I am trying to use a code...which I may have out in the wrong place, where by if someone deselects the "shared workbook" box...to make it exclusive a warning message comes up BEFORE the workbook becomes exclusive asking you the save the history if you select YES this means you have already saved history, then the workbook DOES become exclusive if you select NO then you exit the SUB

This is the code I have but it does not work for me..any ideas ?

Private Sub Worksheet_Deactivate()
rsp = MsgBox("Deactivated. Save changes ?", vbYesNoCancel)
If rsp = vbCancel Then Exit Sub
If rsp = vbYes Then
'do something
Else
' do something else
End If
End Sub