Ironruby BitmapImage ImageOpened event
===

This code

    uri=Uri.new(@header_image, UriKind.Relative)		
    bi=BitmapImage.new(uri)
    bi_opened=bi.GetType.get_event("ImageOpened")
    on_bi_opened = System::EventHandler.new { |sender, e|
      HtmlPage.Window.Alert("Loaded")
    }
    bi_opened.add_event_handler(bi, on_bi_opened)
get an error  
    
    ArgumentException: Can't convert object of type "System.EventHandler" to type "System.EventHandler` 1 [System.Windows.RoutedEventArgs] ".  
How i can catch ImageOpened event in IronRuby?