title: Django preview, TypeError: 'str' object is not callable
body: <p>I'm trying to make a Preview function. I'm reading this blog, <a href="http://latherrinserepeat.org/2008/7/28/stupid-simple-django-admin-previews/" rel="nofollow noreferrer">Django Admin Preview</a>, but now I have the following error and I don't know what it means.</p>
  
  <pre><code>    Traceback (most recent call last):
  
       File "/home/user/webapps/django/lib/python2.5/django/core/handlers/base.py", line 92, in get_response
         response = callback(request, *callback_args, **callback_kwargs)
  
      TypeError: 'str' object is not callable
  </code></pre>
  
  <p>I'm lost..</p>
  
  <p>Edit:</p>
  
  <p>Thanks guys/gals, here is my view.py and url.py:</p>
  
  <pre><code>    from diligencia.diligencias.views import preview
  
      url(r'^admin/diligencias/diligencia/(?P&lt;object_id&gt;\d+)/preview/$','preview'),
      (r'^admin/(.*)', admin.site.root),
  
      from diligencia.diligencias.models import Diligencia
  
      @staff_member_required
      def preview(request, object_id):
          return object_detail(request, object_id=object_id,queryset=Diligencia.objects.all(), template_object_name = 'diligencia_detail.html', )
  </code></pre>