When I use pymongo2.8, There is a error(pymongo.errors.OperationFailure: None)

Question

When I run code like this:

#!/bin/env python
#encoding:utf-8
import sys
sys.path.append('/usr/lib64/python2.7/site-packages')
print sys.path
from pymongo import MongoClient

client = MongoClient('localhost', 27017)
db = client.guping

the output is:

Traceback (most recent call last):
    File "test_mongo.py", line 8, in <module>
    client = MongoClient('localhost', 27017)
  File "/usr/lib64/python2.7/site-packages/pymongo/mongo_client.py", line     374, in __init__
    self._ensure_connected(True)
  File "/usr/lib64/python2.7/site-packages/pymongo/mongo_client.py", line 939, in _ensure_connected
    self.__ensure_member()
  File "/usr/lib64/python2.7/site-packages/pymongo/mongo_client.py", line 813, in __ensure_member
    member, nodes = self.__find_node()
  File "/usr/lib64/python2.7/site-packages/pymongo/mongo_client.py", line 873, in __find_node
member, nodes = self.__try_node(candidate)
  File "/usr/lib64/python2.7/site-packages/pymongo/mongo_client.py", line 720, in __try_node
    {'ismaster': 1})
  File "/usr/lib64/python2.7/site-packages/pymongo/mongo_client.py", line 703, in __simple_command
helpers._check_command_response(response, None, msg)
   File "/usr/lib64/python2.7/site-packages/pymongo/helpers.py", line 133, in _check_command_response
  response)
pymongo.errors.OperationFailure: None

The env:

• python 2.7
• pymongo 2.8

When I run the code on windows8, it's worked well but run on VPS(centos),there is always something wrong

---

I use pymongo 3.0.2 , there is a error like this: pymongo.errors.ServerSelectionTimeoutError: No servers found yet

I can't solve it, so change to pymongo 2.8

But there still err...

I hope someone can help me.