title: Sandcastle Help File Builder Can't Find documentation source
body: <p>I'm building the doc of a VS 2010 C# project with the Sandcastle Help File Builder. I've added the <code>.xml</code> documentation generated by the compiler and the Visual Studio solution <code>.sln</code> file of the project to the <strong>Documentation Sources</strong>. I have also added the project's executable <code>.exe</code> to <strong>References</strong>. However, It is not building. I get these warnings and errors:</p>
  
  <blockquote>
    <p><strong>SHFB: Warning BE0006:</strong> Unable to locate any documentation sources for 'C:\Users\user\Music\Documents\Visual Studio 2010\Projects\SFML_Platformer\SFML_Platformer.sln' (Configuration: Debug Platform: AnyCPU)</p>
    
    <p><strong>SHFB: Error BE0042:</strong> You must specify at least one documentation source in the form of an assembly or a Visual Studio solution/project file</p>
  </blockquote>
  
  <p>What's the problem?</p>