Im chat is not enabled getting same import error in windows

C:\openerp\server\server>openerp-server --gevent
Traceback (most recent call last):
 File "C:\python26\lib\site-packages\py2exe\boot_common.py", line 92, in <modul
 e>
 File "linecache.pyc", line 9, in <module>
    i    Nt
  File "C:\openerp\server\server\.\os.py", line 11, in <module>
    from gevent.hub import get_hub, reinit
  File "C:\openerp\server\server\.\gevent\__init__.py", line 35, in <module>
    from gevent.hub import get_hub, iwait, wait, PYPY
  File "C:\openerp\server\server\.\gevent\hub.py", line 8, in <module>
    import greenlet  # http://pypi.python.org/pypi/greenlet/
  File "C:\openerp\server\server\.\greenlet.py", line 4, in <module>
    from gevent.hub import greenlet, getcurrent, get_hub, GreenletExit, Waiter,
PY3, iwait, wait
ImportError: cannot import name greenlet
Traceback (most recent call last):
  File "openerp-server", line 2, in <module>
  File "C:\openerp\server\server\.\openerp\__init__.py", line 30, in <module>
    import os
  File "C:\openerp\server\server\.\os.py", line 11, in <module>
    from gevent.hub import get_hub, reinit
  File "C:\openerp\server\server\.\gevent\__init__.py", line 35, in <module>
    from gevent.hub import get_hub, iwait, wait, PYPY
  File "C:\openerp\server\server\.\gevent\hub.py", line 8, in <module>
    import greenlet  # http://pypi.python.org/pypi/greenlet/
  File "C:\openerp\server\server\.\greenlet.py", line 4, in <module>
    from gevent.hub import greenlet, getcurrent, get_hub, GreenletExit, Waiter,
PY3, iwait, wait
ImportError: cannot import name greenlet