I'm trying to run example from Celery documentation.

I run: celeryd --loglevel=INFO

/usr/local/lib/python2.7/dist-packages/celery/loaders/default.py:64: NotConfigured: No 'celeryconfig' module found! Please make sure it exists and is available to Python.
  "is available to Python." % (configname, )))
[2012-03-19 04:26:34,899: WARNING/MainProcess]  

 -------------- celery@ubuntu v2.5.1
---- **** -----
--- * ***  * -- [Configuration]
-- * - **** ---   . broker:      amqp://guest@localhost:5672//
- ** ----------   . loader:      celery.loaders.default.Loader
- ** ----------   . logfile:     [stderr]@INFO
- ** ----------   . concurrency: 4
- ** ----------   . events:      OFF
- *** --- * ---   . beat:        OFF
-- ******* ----
--- ***** ----- [Queues]
 --------------   . celery:      exchange:celery (direct) binding:celery

tasks.py:

# -*- coding: utf-8 -*-
from celery.task import task

@task
def add(x, y):
    return x + y

run_task.py:

# -*- coding: utf-8 -*-
from tasks import add
result = add.delay(4, 4)
print (result)
print (result.ready())
print (result.get())

In same folder celeryconfig.py:

CELERY_IMPORTS = ("tasks", )
CELERY_RESULT_BACKEND = "amqp"
BROKER_URL = "amqp://guest:guest@localhost:5672//"
CELERY_TASK_RESULT_EXPIRES = 300

When I run "run_task.py":

on python console

eb503f77-b5fc-44e2-ac0b-91ce6ddbf153
False

errors on celeryd server

[2012-03-19 04:34:14,913: ERROR/MainProcess] Received unregistered task of type 'tasks.add'.
The message has been ignored and discarded.

Did you remember to import the module containing this task?
Or maybe you are using relative imports?
Please see http://bit.ly/gLye1c for more information.

The full contents of the message body was:
{'retries': 0, 'task': 'tasks.add', 'utc': False, 'args': (4, 4), 'expires': None, 'eta': None, 'kwargs': {}, 'id': '841bc21f-8124-436b-92f1-e3b62cafdfe7'}

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/celery/worker/consumer.py", line 444, in receive_message
    self.strategies[name](message, body, message.ack_log_error)
KeyError: 'tasks.add'

Please explain what's the problem.