title: AssertionError: Importing test library 'Dialogs' failed: ImportError: No module named _tkinter
body: <p>I trying to debug a Robot Framework test on my Plone add-on package by using the following as I found in the <a href="http://docs.plone.org/external/plone.app.robotframework/docs/source/debugging.html" rel="nofollow">documentation</a>:</p>
  
  <pre class="lang-none prettyprint-override"><code>*** Settings ***
  
  Resource  plone/app/robotframework/keywords.robot
  
  *** Test Cases ***
  
  Pause tests with included Pause-keyword
     Pause
  </code></pre>
  
  <p>When the test is run the following error is shown:</p>
  
  <pre><code>Failure in test Test Locking Behavior (test_locking_behavior.robot)
  Traceback (most recent call last):
    File "/home/hvelarde/.buildout/eggs/unittest2-0.5.1-py2.7.egg/unittest2/case.py", line 340, in run
      testMethod()
    File "/home/hvelarde/.buildout/eggs/robotsuite-1.6.1-py2.7.egg/robotsuite/__init__.py", line 455, in runTest
      assert last_status == 'PASS', last_message
  AssertionError: Importing test library 'Dialogs' failed: ImportError: No module named _tkinter
  Traceback (most recent call last):
    File "/home/hvelarde/.buildout/eggs/robotframework-2.8.4-py2.7.egg/robot/libraries/Dialogs.py", line 38, in &lt;module&gt;
      from dialogs_py import MessageDialog, PassFailDialog, InputDialog, SelectionDialog
    File "/home/hvelarde/.buildout/eggs/robotframework-2.8.4-py2.7.egg/robot/libraries/dialogs_py.py", line 17, in &lt;module&gt;
      from Tkinter import (Tk, Toplevel, Frame, Listbox, Label, Button, Entry,
    File "/home/hvelarde/buildout.python/parts/opt/lib/python2.7/lib-tk/Tkinter.py", line 39, in &lt;module&gt;
      import _tkinter # If this fails your Python may not be configured for Tk
  PYTHONPATH:
    /home/hvelarde/.buildout/eggs/robotframework-2.8.4-py2.7.egg/robot/libraries
    /home/hvelarde/.buildout/eggs/robotframework-2.8.4-py2.7.egg
    /home/hvelarde/.buildout/eggs/Plone-4.3.4-py2.7.egg
    /home/hvelarde/.buildout/eggs/Products.ATContentTypes-2.1.14-py2.7.egg/Products/ATContentTypes/thirdparty
    /home/hvelarde/.buildout/eggs/plone.app.upgrade-1.3.7-py2.7.egg
    /home/hvelarde/collective/nitf/src
      [ Message content over the limit has been removed. ]
    /home/hvelarde/collective/nitf/bin
    /home/hvelarde/buildout.python/python-2.7/lib/python27.zip
    /home/hvelarde/buildout.python/python-2.7/lib/python2.7
    /home/hvelarde/buildout.python/python-2.7/lib/python2.7/plat-linux2
    /home/hvelarde/buildout.python/python-2.7/lib/python2.7/lib-tk
    /home/hvelarde/buildout.python/python-2.7/lib/python2.7/lib-old
    /home/hvelarde/buildout.python/python-2.7/lib/python2.7/lib-dynload
    /home/hvelarde/buildout.python/parts/opt/lib/python2.7
    /home/hvelarde/buildout.python/parts/opt/lib/python2.7/plat-linux2
    /home/hvelarde/buildout.python/parts/opt/lib/python2.7/lib-tk
    /home/hvelarde/buildout.python/python-2.7/lib/python2.7/site-packages
    /home/hvelarde/buildout.python/parts/opt/lib/python2.7/site-packages/setuptools-2.2-py2.7.egg
    /home/hvelarde/buildout.python/parts/opt/lib/python2.7/site-packages/pip-1.5.6-py2.7.egg
    /home/hvelarde/buildout.python/parts/opt/lib/python2.7/site-packages/Pillow-2.6.0-py2.7-linux-x86_64.egg
    /home/hvelarde/buildout.python/parts/opt/lib/python2.7/site-packages
    .
    /home/hvelarde/collective/nitf/parts/test
  </code></pre>
  
  <p>I already have Tkinter installed in my system:</p>
  
  <pre class="lang-none prettyprint-override"><code># sudo apt-get install python-tk
  Lendo listas de pacotes... Pronto
  Construindo árvore de dependências       
  Lendo informação de estado... Pronto
  python-tk já é a versão mais nova.
  python-tk configurado para instalar manualmente.
  Os seguintes pacotes foram automaticamente instalados e não são mais necessários:
    linux-headers-3.13.0-39 linux-headers-3.13.0-39-generic
    linux-image-3.13.0-39-generic linux-image-extra-3.13.0-39-generic
  Use 'apt-get autoremove' to remove them.
  0 pacotes atualizados, 0 pacotes novos instalados, 0 a serem removidos e 13 não atualizados.
  </code></pre>
  
  <p>How can I fix this?</p>