search by ObjectId in mongodb with pymongo

I need to search an ObjectId with python using pymongo but I always get this error. Any ideas how to search?

import pymongo
from pymongo import MongoClient
from pymongo import ObjectId

gate = collection.find({'_id': ObjectId(modem["dis_imei"])})
print gate

    Traceback (most recent call last):
  File "C:UsersgerswinDocumentsProyectosDemonio pytest.py", line 2, in <module>
    import pymongo
  File "C:Python27libsite-packagespymongo__init__.py", line 80, in <module>
    from pymongo.connection import Connection
  File "C:Python27libsite-packagespymongoconnection.py", line 39, in <module>
    from pymongo.mongo_client import MongoClient
  File "C:Python27libsite-packagespymongomongo_client.py", line 45, in <module>
    from pymongo import (auth,
  File "C:Python27libsite-packagespymongodatabase.py", line 22, in <module>
    from pymongo.collection import Collection
  File "C:Python27libsite-packagespymongocollection.py", line 25, in <module>
    from pymongo.cursor import Cursor
  File "C:Python27libsite-packagespymongocursor.py", line 19, in <module>
    from bson import RE_TYPE
ImportError: cannot import name RE_TYPE