Help on SystemError (Parent module 'google.appengine.ext.db' not loaded)

[heavyz]

Hi,

I installed Google App Engine and tried some examples from the Getting
Started page on a local machine. Everyting works well. Then i tried to
deploy my dummy app to App Engine ( http://bug-garden.appspot.com/sandbox
), and got a strange error when visiting the 'using_datastore' page:

(URL that raised the SystemError: http://bug-garden.appspot.com/sandbox/using_datastore
)

Traceback (most recent call last):
File "/base/python_lib/versions/1/google/appengine/ext/webapp/
__init__.py", line 484, in __call__
handler.get(*groups)
File "/base/data/home/apps/bug-garden/1.2/sandbox/
using_datastore.py", line 25, in get
greetings = db.GqlQuery('SELECT * FROM Greeting ORDER BY date DESC
LIMIT 10')
File "/base/python_lib/versions/1/google/appengine/ext/db/
__init__.py", line 1496, in __init__
from google.appengine.ext import gql
SystemError: Parent module 'google.appengine.ext.db' not loaded

The using_datastore.py is almost the same as described in the Getting
Started page.
Anyone could help?
Thanks!

- zzheng