Inserting a signature and signing a PDF with VBA

I have been searching in different boards about this need that I have. Using code I found in Excel forums and also this forum I got the following code, that works for inserting a signature but failed on the process of signing, and that's why I wrote that in the title.

Sub SignPDF()
On Error GoTo Err_Handler
Dim pdfPDDoc As New AcroPDDoc, oJS As Object, oSign As Object, oPpklite As Object, oFields As Object
Dim strFName1 As String, strFName2 As String, strSignFName As String
Dim oSignInfo As Object, strSecInfo As String
Dim oParam As Parameter
    
   strSignFName = "C:\mySignature.pfx"
   strFName1 = "C:\myPdf.pdf"
   strFName2 = "C:\myPdf-signed.pdf"

   Set pdfPDDoc = CreateObject("AcroExch.PDDoc")
    
   If pdfPDDoc.Open(strFName1) Then
      Set oJS = pdfPDDoc.GetJSObject
      
      Set oFields = oJS.AddField("SignatureField", "signature", 0, Array(350, 800, 500, 750))
      Set oSign = oJS.GetField("SignatureField")
      
      Set oPpklite = oJS.security.getHandler("Adobe.PPKLite", True)
      oPpklite.login "{'myPasswd', '" & strSignFName & "'}"
      oSign.signatureSign oPpklite
      
      pdfPDDoc.Save 1, strFName2
      oPpklite.logout
   End If
   
Exit_Proc:
    Exit Sub
        
Err_Handler:
    MsgBox "In test" & vbCrLf & Err.Number & "--" & Err.Description
    Resume Exit_Proc
End Sub

The problem is in the line with "oSign.signatureSign oPpklite". If I leave as it is, it does not sign the PDF. But if try to add any option, as I read in the Acrobat JavaScript Scripting Reference, it returns an error. This is what I tried:

oSign.signatureSign oPpklite, "{password:'myPasswd', mdp: allowNone}"

It always return an error, no matter what I tried.

Anybody has experience with this task?

(I also asked three days ago in an Excel forum, without success)