Why doesn't this call back function get called?

Why doesn't this call back function get called?

Basically here is the code surrounding the declaratoini callback method:

	webbrowser1 = new WebBrowser();

	webbrowser1.LoadCompleted +=webbrowser1_LoadCompleted;

	webbrowser1.Navigate(new Uri("http://www.google.com"));

Should there be something more or are they in the wrong order?
The method, webbrowser1_LoadCompleted, is never called. I have put breakpoints in the callback method and the running program never reaches this method:

         void webbrowser1_LoadCompleted(object sender, NavigationEventArgs e)
        {
            .
            .
            .

        }

I must be missing a reference. I do not know what one I am missing. Can you offer a suggestion?