powervc driver cinder-volume fail to start up

while start cinder-volume for powervc driver, it fails:
2014-09-03 21:38:22.570 28098 TRACE cinder File "/usr/bin/cinder-volume", line 77, in <module>
2014-09-03 21:38:22.570 28098 TRACE cinder server = service.Service.create(binary='cinder-volume')
2014-09-03 21:38:22.570 28098 TRACE cinder File "/usr/lib/python2.6/site-packages/cinder/service.py", line 242, in create
2014-09-03 21:38:22.570 28098 TRACE cinder service_name=service_name)
2014-09-03 21:38:22.570 28098 TRACE cinder File "/usr/lib/python2.6/site-packages/cinder/service.py", line 126, in __init__
2014-09-03 21:38:22.570 28098 TRACE cinder *args, **kwargs)
2014-09-03 21:38:22.570 28098 TRACE cinder File "/usr/lib/python2.6/site-packages/cinder/volume/manager.py", line 184, in __init__
2014-09-03 21:38:22.570 28098 TRACE cinder self.driver = profiler.trace_cls("driver")(self.driver)
2014-09-03 21:38:22.570 28098 TRACE cinder File "/usr/lib/python2.6/site-packages/osprofiler/profiler.py", line 139, in decorator
2014-09-03 21:38:22.570 28098 TRACE cinder for attr_name, attr in inspect.getmembers(cls):
2014-09-03 21:38:22.570 28098 TRACE cinder File "/usr/lib64/python2.6/inspect.py", line 252, in getmembers
2014-09-03 21:38:22.570 28098 TRACE cinder value = getattr(object, key)
2014-09-03 21:38:22.570 28098 TRACE cinder File "/usr/lib/python2.6/site-packages/cinder/volume/driver.py", line 269, in initialized
2014-09-03 21:38:22.570 28098 TRACE cinder return self._initialized
2014-09-03 21:38:22.570 28098 TRACE cinder AttributeError: 'PowerVCDriver' object has no attribute '_initialized'
2014-09-03 21:38:22.570 28098 TRACE cinder