Ошибка подключения MongoLab/PyMongo

если я бегу в оболочке:

mongo ds0219xx.mlab.com:219xx/dbname -u user -p pass

он работает и позволяет мне подключаться к базе данных и вытягивать информацию. Но если я нахожусь в своем приложении python (Flask) и запускаю это:

import pymongo

client = pymongo.MongoClient("mongodb://user:pass@ds0219xx.mlab.com:219xx/dbname")

db = client["dbname"]

db.users.insert_one({
  "user1": "hello"
})

это дает мне:

pymongo.errors.OperationFailure: Authentication failed.

Я уверен, что он терпит неудачу, прежде чем он доберется до вызова insert_one (), но я не совсем уверен.

спасибо!

изменить: По запросу, здесь полный вызов:

Traceback (most recent call last):
File "run.py", line 1, in <module>
from app import app
File "/Users/Derek/Documents/programming/shenalum/app/__init__.py", line 6, in <module>
from app import views
File "/Users/Derek/Documents/programming/shenalum/app/views.py", line 4, in <module>
from data import get_posts, get_user_info
File "/Users/Derek/Documents/programming/shenalum/app/data.py", line 9, in <module>
"user1": "hello"
File "/usr/local/lib/python2.7/site-packages/pymongo/collection.py", line 622, in insert_one
with self._socket_for_writes() as sock_info:
File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/contextlib.py", line 17, in __enter__
return self.gen.next()
File "/usr/local/lib/python2.7/site-packages/pymongo/mongo_client.py", line 718, in _get_socket
with server.get_socket(self.__all_credentials) as sock_info:
File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/contextlib.py", line 17, in __enter__
return self.gen.next()
File "/usr/local/lib/python2.7/site-packages/pymongo/server.py", line 152, in get_socket
with self.pool.get_socket(all_credentials, checkout) as sock_info:
File "/usr/local/Cellar/python/2.7.11/Frameworks/Python.framework/Versions/2.7/lib/python2.7/contextlib.py", line 17, in __enter__
return self.gen.next()
File "/usr/local/lib/python2.7/site-packages/pymongo/pool.py", line 541, in get_socket
sock_info.check_auth(all_credentials)
File "/usr/local/lib/python2.7/site-packages/pymongo/pool.py", line 306, in check_auth
auth.authenticate(credentials, self)
File "/usr/local/lib/python2.7/site-packages/pymongo/auth.py", line 436, in authenticate
auth_func(credentials, sock_info)
File "/usr/local/lib/python2.7/site-packages/pymongo/auth.py", line 416, in _authenticate_default
return _authenticate_scram_sha1(credentials, sock_info)
File "/usr/local/lib/python2.7/site-packages/pymongo/auth.py", line 188, in _authenticate_scram_sha1
res = sock_info.command(source, cmd)
File "/usr/local/lib/python2.7/site-packages/pymongo/pool.py", line 213, in command
read_concern)
File "/usr/local/lib/python2.7/site-packages/pymongo/network.py", line 99, in command
helpers._check_command_response(response_doc, None, allowable_errors)
File "/usr/local/lib/python2.7/site-packages/pymongo/helpers.py", line 196, in _check_command_response
raise OperationFailure(msg % errmsg, code, response)

pymongo.ошибки.OperationFailure: ошибка проверки подлинности.