Update assignment with Excel(vba)

Private Sub CommandButton1_Click()

' Launch PC-Dmis by creating the app object
Dim App As Object
Set App = CreateObject("PCDLRN.Application")
If Not App.WaitUntilReady(300) Then
    MsgBox "Machine did not initialize, Exiting"
Exit Sub
End If

'if you get here, the machine initialized successfuly
' Ask the App object for the partprograms object
Dim Parts As Object
Set Parts = App.PartPrograms
App.Visible = True
App.SetActive
App.Maximize
' Ask the Partprograms object to display the file
' open dialog and return the opened part program object
Dim Part As Object
' Set Part = Parts.Open("c:\tmp\lot.prg", "CMM1")
Set Part = Parts.Open("c:\tmp\lot.prg", "OFFLINE")
App.Visible = True
App.SetActive
App.Maximize


Dim Act_Part As Object
Set Act_Part = App.ActivePartProgram
Dim Cmds As Object
Dim Cmd As Object
Set Cmds = Act_Part.Commands
Dim lot_number As String

lot_number = "0025"

For Each Cmd In Cmds
    MsgBox "did i get here - looking at commands"
    If Cmd.Type = ASSIGNMENT Then
        MsgBox "did i get here - found assign command"
        If Cmd.GetText(DEST_EXPR, 0) = "LOTNUM" Then
            bln = Cmd.PutText("""" + lot_number + """", SRC_EXPR, 0)
            Cmd.ReDraw
        End If
    End If
Next Cmd




' Execute the opened part program
'Part.Execute
' Close the part program
'Part.Close
' Quit the Application (shut down PC-Dmis)
'App.Quit
End Sub