Run sovrin error

[xzcccc]

I install the sovrin-node by $ pip install -U --no-cache-dir sovrin-client . (And this command is follow the guide form https://www.evernym.com)
However, when I run the sovrin, it was something error. As follow is the error code:

(sovrin) [xzc@xzc ~]$ sovrin
Loading module /home/xzc/anaconda3/lib/python3.6/site-packages/config/config-crypto-example1.py
Module loaded.
Traceback (most recent call last):
  File "/home/xzc/anaconda3/bin/sovrin", line 37, in <module>
    from sovrin_client.cli.cli import SovrinCli
  File "/home/xzc/anaconda3/lib/python3.6/site-packages/sovrin_client/cli/cli.py", line 17, in <module>
    from plenum.cli.cli import Cli as PlenumCli
  File "/home/xzc/anaconda3/lib/python3.6/site-packages/plenum/cli/cli.py", line 82, in <module>
    from plenum.server.node import Node
  File "/home/xzc/anaconda3/lib/python3.6/site-packages/plenum/server/node.py", line 71, in <module>
    from plenum.server.monitor import Monitor
  File "/home/xzc/anaconda3/lib/python3.6/site-packages/plenum/server/monitor.py", line 24, in <module>
    pluginManager = PluginManager()
  File "/home/xzc/anaconda3/lib/python3.6/site-packages/plenum/server/notifier_plugin_manager.py", line 35, in __init__
    self.importPlugins()
  File "/home/xzc/anaconda3/lib/python3.6/site-packages/plenum/server/notifier_plugin_manager.py", line 79, in importPlugins
    plugins = self._findPlugins()
  File "/home/xzc/anaconda3/lib/python3.6/site-packages/plenum/server/notifier_plugin_manager.py", line 105, in _findPlugins
    for pkg in pip.utils.get_installed_distributions()
AttributeError: module 'pip' has no attribute 'utils'

Howeverm,when i go to python console by type python and import pip.utils, it works ok.

(sovrin) [xzc@xzc ~]$ python
Python 3.6.4 |Anaconda, Inc.| (default, Jan 16 2018, 18:10:19) 
[GCC 7.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pip.utils
>>> pip.utils
<module 'pip.utils' from '/home/xzc/.virtualenvs/sovrin/lib/python3.6/site-packages/pip/utils/__init__.py'>
>>> pip.utils.get_installed_distributions()
[wheel 0.31.1 (/home/xzc/.virtualenvs/sovrin/lib/python3.6/site-packages), setuptools 39.2.0 (/home/xzc/.virtualenvs/sovrin/lib/python3.6/site-packages), pip 9.0.1 (/home/xzc/.virtualenvs/sovrin/lib/python3.6/site-packages)]

Python version:3.6.4
Pip version:9.0.1
OS version:Centos7

THANKS