For performance reasons I'm converting a large list of images into a single image. This code does exactly what I want. Private Function FlattenControl(Control As UIElement) As Image Control.Measure(New Size(1000, 1000)) Control.Arrange(New Rect(0, 0, 1000, 1000)) Dim ImgSource As New Imaging.WriteableBitmap(1000, 1000) ImgSource.Render(Control, New TranslateTransform) ImgSource.Invalidate Dim Img As New Image Img.Source = ImgSource Return Img End Function I can add all the images into a canvas pass the canvas to this function and I get back one image. My code to load all the images looks like this. Public Function BuildTextures(Layer As GLEED2D.Layer) As FrameworkElement Dim Container As New Canvas For Each Item In Layer.Items If TypeOf Item Is GLEED2D.TextureItem Then Dim Texture = CType(Item, GLEED2D.TextureItem) Dim Url As New Uri(Texture.texture_filename, UriKind.Relative) Dim Img As New Image Img.Source = New Imaging.BitmapImage(Url) Container.Children.Add(Img) End If Next Return FlattenControl(Container) End Function The GLEED2D.Layer and GLEED2D.TextureItem classes are from the free level editor GLEED2D (http://www.gleed2d.de/). The texture_filename on every TextureItem is "Images/tree_clipart_pine_tree.png" This works just fine, but it's just a proof of concept. What I really need to do (among other things) is have the path to the image hard coded. If I replace Texture.texture_filename in the code above with the string literal "Images/tree_clipart_pine_tree.png" the images do not appear in the final merged image. I can add a breakpoint and see that the WriteableBitmap has all of it's pixels as 0 after the call to Invalidate. I have no idea how this could cause any sort of difference, but it gets stranger. If I remove the call to FlattenControl and just return the Canvas instead, the images are visible. It's only when I use the string literal with the WriableBitmap that the images do not appear. I promise you that the value in the texture_filename property is exactly "Images/tree_clipart_pine_tree.png". I'm using Silverlight 3 and I've also reproduced this in Silverlight 4. Any ideas?