ADOX and Append User

This code is taken straight from MSDN. However, when it tries to execute the Append method into an Access XP database, I get "Err 3251, Object or provider is not capable of performing requested operation."

Code:

---

    Dim cat As ADOX.Catalog
    Dim usrNew As ADOX.User
   
    Set cat = New ADOX.Catalog
    cat.ActiveConnection = "Provider=MICROSOFT.JET.OLEDB.4.0;" _
                & "Jet OLEDB:System database=mySystem.mdw;" _
                & "User ID=admin;" _
                & "Password=admin;" _
                & "Persist Security Info=True;" _
                & "Data Source=myDB.mdb"
   
    With cat
     
        ' Create and append new user with an object.
        Set usrNew = New ADOX.User
        usrNew.Name = "PatSmith"
        usrNew.ChangePassword "", "password1"
        .Users.Append usrNew

    End With

---

Anyone have an idea??