Webbrowser control's window.external is ALWAYS null

Option Strict Off

Public Class Form1
    Private Sub Form1_Load()
        Handles MyBase.LoadMe.WebBrowser1.Document.Window.DomWindow.External.AddFavorite("http://www.google.com")
    End Sub
End Class

[PermissionSet(SecurityAction.Demand, Name = "FullTrust")]
[ComVisible(true)]