title: PhpStorm says it doesn't recognize Doctrine's ORM namespace
body: <p>I'm working on a project using Symfony2 and I'm coding in PhpStorm. For some reason, PhpStorm is complaining about this line:</p>
  
  <pre><code>use Doctrine\ORM\Mapping as ORM;
  </code></pre>
  
  <p>It highlights "ORM" red and says "Unrecognized namespace ORM". A previous occasion when I had this message, I realized that the Symfony2 plugin for PhpStorm was disabled, and turning it on seemingly fixed it. This time, however, it was already enabled. Does anyone know another issue that could be causing this message? (sorry this question is a bit broad, I don't really know what else to try to fix it)</p>