Проблема с Django-1.3 beta

Ребята !! Я с большим энтузиазмом изучал django и немного изучил Django-1.2, но затем я установил версию 1.3, и это нормально, пока я не запустил сервер с помощью команды «python manage.py runserver». Это дает огромную ошибку. Я не могу найти способ решить эту проблему. И ошибка отображается как:

Traceback (most recent call last):    

  File "manage.py", line 11, in <module>    
    execute_manager(settings)    
  File "/usr/local/lib/python2.6/dist-packages/django/core/management/__init__.py", line 438, in execute_manager    
    utility.execute()    
  File "/usr/local/lib/python2.6/dist-packages/django/core/management/__init__.py", line 379, in execute  
    self.fetch_command(subcommand).run_from_argv(self.argv)  
  File "/usr/local/lib/python 2.6/dist-packages/django/core/management/__init__.py", line 261, in fetch_command   
    klass = load_command_class(app_name, subcommand)    
  File "/usr/local/lib/python2.6/dist-packages/django/core/management/__init__.py", line   67, in load_command_class    
    module = import_module('%s.management.commands.%s' % (app_name, name))    
  File "/usr/local/lib/python2.6/dist-packages/django/utils/importlib.py", line 35, in   import_module    
    __import__(name)    
  File "/usr/local/lib/python2.6/dist-packages/django/core/management/commands    /runserver.py", line 8, in <module>    
    from django.core.handlers.wsgi import WSGIHandler  
  File "/usr/local/lib/python2.6/dist-packages/django/core/handlers/wsgi.py", line 11, in <module>    
    from django.core import signals   
  File "/usr/local/lib/python2.6/dist-packages/django/core/signals.py", line 1, in <module>
    from django.dispatch import Signal   
  File "/usr/local/lib/python2.6/dist-packages/django/dispatch/__init__.py", line 9, in <module>    
    from django.dispatch.dispatcher import Signal, receiver    
ImportError: cannot import name receiver