I'm trying to add a controlbutton to the popup menu when you right click a
worksheet.
I've got the following sub working when I run it from one worksheet but when
I put it into another one (a template) it doesn't work and I get an "Invalid
procedure call or argument" error. When I debug it in the first sheet the
value for msoControlButton = 1, but when in the template it is empty.

Sub add_menu_item()
delete_menu_item
With Application.CommandBars("Cell").Controls
With .Add(msoControlButton)
.Caption = "My Item"
.OnAction = "my_macro"
End With
End With
End Sub

Private Sub my_macro()
MsgBox ("Hello")
End Sub