Check this out:

// Create background image component if we got background
if (_backgroundData != null)
{
   _backgroundComponent = new BitmapImage();
   _backgroundComponent.smooth = true;
   _backgroundComponent.fillMode = BitmapFillMode.REPEAT;
   _backgroundComponent.width = _size.x;
   _backgroundComponent.height = _size.y;
   addElement(_backgroundComponent);
}

Does anyone see _backgroundComponent.source = _backgroundData ? Not me! I should sometimes shoot myself...