title: All projects referencing sub-project must install NuGet package Microsoft.Bcl.Build (C#/Windows Phone 7)?
body: <p>I'm having a particularly difficult refactoring session involving a C# solution with multiple projects in Visual Studio 2012.  I needed to pull out a bunch of code into their own assemblies so that code could be shared across several projects, all in the same solution.  However, no matter what I try, I get warnings for the projects that reference the new shared projects that "All projects referencing {shared project name} must install nuget package Microsoft.Bcl.Build".</p>
  
  <p>I have been over the dependent projects and the shared projects with a fine-tooth comb, verifying in detail that they all use the same version and exact same DLL for the Microsoft.Bcl version 1.0.1.19 and Microsoft.Bcl.Async version 1.0.16 packages:</p>
  
  <ul>
  <li>System.Runtime</li>
  <li><p>System.Threading.Tasks</p></li>
  <li><p>Microsoft.Threading.Task</p></li>
  <li>Microsoft.Threading.Tasks.Extensions</li>
  <li>Microsoft.Threading.Tasks.Extensions.Phone</li>
  </ul>
  
  <p>The DLL paths are all resolved and identical.  The XAP file does build but I still get that warning telling me that Microsoft.Bcl.Build is not referenced in the dependent projects, despite the fact that I can see that it is.</p>
  
  <p>If I try instead to uninstall and then reinstall those two packages using NuGet for each project involved, I get references with empty paths and the warning icon for the 5 DLL references involved.  For some reason NuGet adds the references but can't find the DLLs.  Also, if I do this, I find myself with the problem frequently of having projects where I get the "Can't add reference" error when trying to add a reference.  Then I have close and re-open the solution, and that leads to a "project failed to load" error.  So I have to edit the project file manually, remove the faulty package import statements, and reload the project.</p>
  
  <p>How can I fix this problem and what is the general technique for avoiding this headache in the future?  Letting NuGet manage missing packages didn't help at al.</p>