Wrong Stamp what ever AP value i use

Hi, 

I found a piece of code on the internet, I'm trying to add a custom stamp on pdf with VBA.

It's working, I mean almost. Changing the property for Rect,Contents,Author or Name I can see the effect on my pdf. The only thing is, it always uses the Draft Stamp, nothing else whatever i pass in the AP property. 

Any idea what i'm doing wrong?

Dim gApp As Acrobat.CAcroApp
Dim gPDDoc As Acrobat.CAcroPDDoc
Dim jso As Object
Dim stampRect(3) As Integer
Dim pageRect As Object
Dim annot As Object
Dim props As Object
Dim page As Object


    Set gApp = CreateObject("AcroExch.App")
    Set gPDDoc = CreateObject("AcroExch.PDDoc")
    If gPDDoc.Open("whatever.pdf") Then
        Set jso = gPDDoc.GetJSObject

        Set page = gPDDoc.AcquirePage(0)
        Set pageRect = page.GetSize

        stampRect(0) = 100
        stampRect(1) = 500
        stampRect(2) = 400
        stampRect(3) = 500
        
        Set annot = jso.AddAnnot
        Set props = annot.getprops
        props.Type = "Stamp"
        annot.setProps props
        
        Set props = annot.getprops
        props.ap = "Test2"
        props.page = 0
        props.rect = stampRect
        annot.setProps props
        
    End If