title: ImportError: "No modules named". But modules already installed in dist-packages
body: <p>I am using python2.7 and trying to import modules such as <b>psycopg2</b>. But I get the following error when I try to import the module:</p>
  
  <pre><code>import psycopg2
  ImportError: No module named psycopg2
  </code></pre>
  
  <p>When I try <b>pip</b> to install the module it gives me the following message:</p>
  
  <pre><code>Requirement already satisfied (use --upgrade to upgrade): psycopg2 in /usr/local/lib/python2.7/dist-packages
  Cleaning up...
  </code></pre>
  
  <p>Can anyone please tell me what I am doing wrong?</p>