Unhandled exception in thread started by <bound method Server._start of <cherrypy._cpserver.Server object at 0xb7c2530c>>
Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/cherrypy/_cpserver.py", line 78, in _start
    Engine._start(self)
  File "/usr/lib/python2.5/site-packages/cherrypy/_cpengine.py", line 110, in _start
    func()
  File "/usr/lib/python2.5/site-packages/turbogears/startup.py", line 234, in startTurboGears
    ext.start_extension()
  File "/usr/lib/python2.5/site-packages/turbogears/visit/api.py", line 155, in start_extension
    create_extension_model()
  File "/usr/lib/python2.5/site-packages/turbogears/visit/api.py", line 174, in create_extension_model
    _manager.create_model()
  File "/usr/lib/python2.5/site-packages/turbogears/visit/savisit.py", line 39, in create_model
    class_mapper(visit_class).local_table.create(checkfirst=True)
  File "/usr/lib/python2.5/site-packages/sqlalchemy/orm/mapper.py", line 1649, in class_mapper
    raise exceptions.InvalidRequestError("Class '%s' entity name '%s' has no mapper associated with it" % (class_.__name__, entity_name))
AttributeError: 'NoneType' object has no attribute '__name__'