title: A module is installed by it says it's not
body: <p>In a virt environment I run a script:</p>
  
  <pre><code>(venv)my_script$ python main.py
  Traceback (most recent call last):
    File "main.py", line 3, in &lt;module&gt;
      import my_script2
    File "/home/me/..../main.py", line 1, in &lt;module&gt;
      import numpy as np
  ImportError: No module named numpy
  </code></pre>
  
  <p>But it's installed:</p>
  
  <pre><code>(venv)my_script$ sudo pip install numpy
  ....
  Requirement already satisfied (use --upgrade to upgrade): numpy in /usr/local/lib/python2.7/dist-packages
  </code></pre>
  
  <p>What's the matter?</p>