Sub addShape()

On Error Resume Next
If ActiveWindow.Selection.ShapeRange(1).HasSmartArt Then
If Err <> 0 Then
MsgBox "select smart art"
Exit Sub
End If
'so far so good
If ActiveWindow.Selection.ChildShapeRange.Count = 1 Then
'One node selected
CommandBars.ExecuteMso ("SmartArtAddShapeAfter")
Else
MsgBox "Select ONE node"
End If
End If 'not Smart art
End Sub