title: Could not get dependencies for project reference
body: <p>I have a C# solution with a website project and a C# library.
  When compiling the solution, the website gives the message:</p>
  
  <p>Could not get dependencies for project reference 'MyLibrary'.</p>
  
  <p>This does not stop the wbsite compiling and running until I try and build it with a TFS build, when this error message fails the build.</p>
  
  <p>What does this mean and how can I get round it?</p>