Loading images in WPF from code

You need one more comma in there. Here is the documentation on Pack URIs in WPF. Notice there are three commas when using the authority.

lResult = new BitmapImage(new Uri(@"pack://application:,,,/Resources/ImageMissing.jpg", UriKind.Absolute));

Did you happen to rename the file (or folder) in the Solution Explorer and then not clean or rebuild the application?

If you're positive the name in your URI matches what is in the Solution Explorer, then try right clicking the solution and selecting "Rebuild".

The problem is the image has not been added to your project - including it in the resources file is not enough.

Right click your project > Add Existing Item > Browse to and find and add the image.

Then all you need to do is:

myImage = new BitmapImage(new Uri(@"ImageMissing.jpg", UriKind.RelativeOrAbsolute));

You probably created this second library as "Class Library" instead "WPF Custom Library". Creating xaml files or embedding images as "Resources" in a class library is not enough for WPF, you are probably missing the following in your AssemblyInfo.cs file:

Properties/AssemblyInfo.cs

[assembly: ThemeInfo(
ResourceDictionaryLocation.None, //where theme specific resource dictionaries are located
  //(used if a resource is not found in the page, 
  // or application resource dictionaries)
  ResourceDictionaryLocation.SourceAssembly //where the generic resource dictionary is located
  //(used if a resource is not found in the page, 
  // app, or any theme specific resource dictionaries)
)]

Try this:

var icon = BitmapFrame.Create(Application.GetResourceStream(
new Uri("MyAppBitmap.jpg", UriKind.RelativeOrAbsolute)).Stream);