title: ERROR: Cannot find all types required by the 'async' modifier. Are you targeting the wrong framework version, or missing a reference to an assembly?
body: <p>I have following configuration of my PC:</p>
  
  <ul>
  <li>Windows 8</li>
  <li>Visual Studio 2012</li>
  <li>.NET Framework 4.5</li>
  </ul>
  
  <p>My Project Configuration is:</p>
  
  <ul>
  <li>WP 7.1</li>
  <li>Silverlight 4.0</li>
  <li>.NET Framework 4.0</li>
  <li>CTP ASYNC (installed, using async and await keywords)</li>
  </ul>
  
  <p>The project was written using VS2010 on Windows 7 machine for WP7.1. Now I have upgraded the PC to Windows 8 and have installed VS2012. </p>
  
  <p>The project, however, complaining about  'async' modifier.</p>
  
  <p>Cannot find all types required by the 'async' modifier. Are you targeting the wrong framework version, or missing a reference to an assembly?</p>
  
  <p>Any idea how to solve this problem?</p>
  
  <p>thank you!</p>