title: phpDocumentor - Unable to find the dot command of the GraphViz package
body: <p>I would like ask some help about my next problem:
  I am working on a Symfony2 project. We installed Symfony2 via composer.
  Now I would like to generate phpDocument used by phpDocumentor.</p>
  
  <p>A did the following steps:</p>
  
  <ol>
  <li>update composer: sudo php composer.phar self-update</li>
  <li><p>add the following property to Symfony2/compose.json file:</p>
  
  <pre><code>"require-dev": {
      "phpdocumentor/phpdocumentor": "2.*@dev"
  },
  </code></pre></li>
  <li><p>Run composer command</p>
  
  <pre><code>sudo php composer.phar update
  </code></pre></li>
  </ol>
  
  <p>Result was success! The installed GraphViz version is: 1.0.2</p>
  
  <p>When I try to generate phpDoc from source code finally I got a message:
  <em>Unable to find the <code>dot</code> command of the GraphViz package. Is GraphViz correctly installed and present in your path?</em>
  (Document generated as right...)</p>
  
  <p>I tried to found a soulution about this problem but I couldn't.<br>
  Is anybody can help me to resolve this problem?</p>
  
  <p>Environment is: Ubuntu release 12.04</p>