title: Hide fields in Django admin
body: <p>I'm tying to hide my slug fields in the admin by setting <strong>editable=False</strong> but every time I do that I get the following error:</p>
  
  <pre><code>KeyError at /admin/website/program/6/
  Key 'slug' not found in Form
  Request Method: GET
  Request URL:    http://localhost:8000/admin/website/program/6/
  Exception Type: KeyError
  Exception Value:    
  Key 'slug' not found in Form
  Exception Location: c:\Python26\lib\site-packages\django\forms\forms.py in __getitem__, line 105
  Python Executable:  c:\Python26\python.exe
  Python Version: 2.6.4
  </code></pre>
  
  <p>Any idea why this is happening</p>