title: windows phone project: missing System.ComponentModel.DataAnnotations
body: <p>I have VS 2012 ultimate and created Windows phone Project 7.1 / 8.0. tried to install Entityframwork</p>
  
  <pre><code>Install-Package EntityFramework -Version 6.0.2
  </code></pre>
  
  <p>but i receive the following error:</p>
  
  <blockquote>
    <p>Installing 'EntityFramework 6.0.2'.
    You are downloading EntityFramework from Microsoft, the license agreement to which is available at <a href="http://go.microsoft.com/fwlink/?LinkID=320539" rel="nofollow">http://go.microsoft.com/fwlink/?LinkID=320539</a>. Check the package for additional dependencies, which may come with their own license agreement(s). Your use of the package and dependencies constitutes your acceptance of their license agreements. If you do not accept the license agreement(s), then delete the relevant components from your device.
    Successfully installed 'EntityFramework 6.0.2'.
    Adding 'EntityFramework 6.0.2' to DataBoundApp3.
    Uninstalling 'EntityFramework 6.0.2'.
    Successfully uninstalled 'EntityFramework 6.0.2'.
    Install failed. Rolling back...
    Install-Package : Failed to add reference to 'System.ComponentModel.DataAnnotations'. Please make sure that it is in the Global Assembly Cache.
    At line:1 char:1
    + Install-Package EntityFramework -Version 6.0.2
    + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        + CategoryInfo          : NotSpecified: (:) [Install-Package], InvalidOperationException
        + FullyQualifiedErrorId : NuGetCmdletUnhandledException,NuGet.PowerShell.Commands.InstallPackageCommand</p>
  </blockquote>
  
  <p>the part <code>System.ComponentModel.DataAnnotations</code> does not appear under Add references. how to solve this issue?</p>