RuntimeError: Unable to locate any configuration file.

When I try keystone-manage tenant add admin,the problem is:
ERROR: Unable to locate any configuration file. Cannot load application admin
ERROR:root:Unable to locate any configuration file. Cannot load application admin
Traceback (most recent call last):
  File "/usr/local/bin/keystone-manage", line 5, in <module>
    pkg_resources.run_script('keystone==2012.1', 'keystone-manage')
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 467, in run_script
    self.require(requires)[0].run_script(script_name, ns)
  File "/usr/lib/python2.7/dist-packages/pkg_resources.py", line 1200, in run_script
    execfile(script_filename, namespace, namespace)
  File "/usr/local/lib/python2.7/dist-packages/keystone-2012.1-py2.7.egg/EGG-INFO/scripts/keystone-manage", line 16, in <module>
    keystone.manage.main()
  File "/usr/local/lib/python2.7/dist-packages/keystone-2012.1-py2.7.egg/keystone/manage/__init__.py", line 288, in main
    raise exc
RuntimeError: Unable to locate any configuration file. Cannot load application admin
Thanks.