Ryu controller run errors un Ubuntu 14.04

root@controller:/home/controller/ryu# ryu-manager /usr/local/lib/python2.7/dist-packages/ryu/app/simple_switch.py
Traceback (most recent call last):
  File "/usr/local/bin/ryu-manager", line 5, in <module>
    from pkg_resources import load_entry_point
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 2749, in <module>
    working_set = WorkingSet._build_master()
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 444, in _build_master
    ws.require(__requires__)
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 725, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 628, in resolve
    raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: rfc3986>=0.2.0