I went through this example here:
http://docs.celeryproject.org/en/latest/django/first-steps-with-django.html
All my tasks are in files called tasks.py.
I got the same error. It turns out there was a problem with my Celery version. I upgraded to 3.1 and celeryd is now deprecated for this version (http://celery.readthedocs.org/en/latest/whatsnew-3.1.html). So I had to downgrade to the version 3.0.19 that was the previous stable version used for the project, and it works good so far.
pip install celery==3.0.19
Anyway, if you don't want to downgrade, the replacement for celeryd in the version 3.1 is celery worker. Check here for more info: http://celery.readthedocs.org/en/latest/userguide/workers.html.
Hope this helps! :)