Check if OnAction is empty

Question

In this link , i use SHP.OnAction (where Dim SHP As Shape ) to print the name of the macro which is assigned to a shape.

Now I would like to check if SHP.OnAction is empty, which means there is no macro assigned to this object. SHP.OnAction = "" does not work, it always return false . I have tried also ``SHP.OnAction = Empty , SHP.OnAction = Null , they always return false` too...

Could anyone tell me how to verify if it is empty?

Edit1: I use the following piece of code, to go through all the shapes in a workbook, and check if there is a shape to that a macro is assigned. I test it with some workbooks containing Chart or Picture , it seems that sShpaes.OnAction <> "" returns always true , even though the shape has no macro...

On Error Resume Next
Dim sShapes As Shape
existsAssignedShape = False

For Each ws In Worksheets
    For Each sShapes In ws.Shapes
        st = ws.Name & "     " & sShapes.Name & "     " & sShapes.OnAction
        Print #1, st
        Print #1, ""
        If (Not existsAssignedShape) And (sShpaes.OnAction <> "") Then
            existsAssignedShape = True
        End If
    Next sShapes
Next ws

Answer 1

If no macro has been assigned to an AutoShape, then the following will indicate True :

Sub hgfd()
    Dim s As Shape, t As String
    Set s = ActiveSheet.Shapes(1)
    t = CStr(s.OnAction)
    MsgBox t = ""
End Sub