No events are fired from an imagebrush via ImageOpened/ImageFailed

Question

A canvas is received from the server, and an image brush is extracted from the canvas via searching for a bunch of pathes. In summary, Canvas -> Path -> Path.Fill -> ImageBrush. Now, I want to take a snapshot of the ImageBrush using WriteableBitmap when it is loaded and here is what I did

var imageBrushes =
VisualTreeUtility.FindVisualChildren<Path>(canvas)
    .Where(i => i.Fill.GetType() == typeof(ImageBrush))
    .Select(p => p.Fill);  
foreach(var image in imageBrushes)  
{
    image.ImageOpened += delegate { //never gets here };
    image.ImageFailed += delegate { //never gets here either };

    // if the image is already loaded
    if (((BitmapSource)image.ImageSource).PixelWidth != 0)
    {
        // never gets here either
    }        
}

As you can see the comments in the code above, no matter what I try, I can't seem to catch an event from the image. Any suggestions?