devstack: rejoin-stack.sh doesn't work

Hi guys, I have a problem with my devstack installation: I need to keep my configuration of openstack even after the reboot of my virtual machine on which there is the installation of openstack..so i'm using the rejoin-stack.sh script, but when I launch it, on the screen I obtain this error:

cd /opt/stack/cinder && /opt/stack/cinder/bin/cinder-volume --config-file /etc/cinder/cinder.conf
user@ubuntu:~/devstack$ cd /opt/stack/cinder && /opt/stack/cinder/bin/cinder-volume --config-file /etc/cinder/cinder.conf
2013-08-08 07:56:18.510 INFO cinder.service [-] Starting 1 workers
2013-08-08 07:56:18.661 INFO cinder.service [-] Started child 4412
2013-08-08 07:56:18.786 AUDIT cinder.service [-] Starting cinder-volume node (version 2013.2)
2013-08-08 07:56:18.867 DEBUG cinder.openstack.common.processutils [req-d8889b98-061b-41e7-9539-1031be41a328 None None] Running cmd (subprocess): sudo cinder-rootwrap /etc/cinder/rootwrap.conf vgs --noheadings -o name from (pid=4412) execute /opt/stack/cinder/cinder/openstack/common/processutils.py:142
2013-08-08 07:56:26.498 ERROR cinder.service [req-d8889b98-061b-41e7-9539-1031be41a328 None None] Unhandled exception
2013-08-08 07:56:26.498 TRACE cinder.service Traceback (most recent call last):
2013-08-08 07:56:26.498 TRACE cinder.service File "/opt/stack/cinder/cinder/service.py", line 228, in _start_child
2013-08-08 07:56:26.498 TRACE cinder.service self._child_process(wrap.server)
2013-08-08 07:56:26.498 TRACE cinder.service File "/opt/stack/cinder/cinder/service.py", line 205, in _child_process
2013-08-08 07:56:26.498 TRACE cinder.service launcher.run_server(server)
2013-08-08 07:56:26.498 TRACE cinder.service File "/opt/stack/cinder/cinder/service.py", line 96, in run_server
2013-08-08 07:56:26.498 TRACE cinder.service server.start()
2013-08-08 07:56:26.498 TRACE cinder.service File "/opt/stack/cinder/cinder/service.py", line 359, in start
2013-08-08 07:56:26.498 TRACE cinder.service self.manager.init_host()
2013-08-08 07:56:26.498 TRACE cinder.service File "/opt/stack/cinder/cinder/volume/manager.py", line 146, in init_host
2013-08-08 07:56:26.498 TRACE cinder.service self.driver.check_for_setup_error()
2013-08-08 07:56:26.498 TRACE cinder.service File "/opt/stack/cinder/cinder/volume/drivers/lvm.py", line 80, in check_for_setup_error
2013-08-08 07:56:26.498 TRACE cinder.service raise exception.VolumeBackendAPIException(data=exception_message)
2013-08-08 07:56:26.498 TRACE cinder.service VolumeBackendAPIException: Bad or unexpected response from the storage volume backend API: volume group stack-volumes doesn't exist
2013-08-08 07:56:26.498 TRACE cinder.service
2013-08-08 07:56:26.615 INFO cinder.service [-] Child 4412 exited with status 2
2013-08-08 07:56:26.628 INFO cinder.service [-] _wait_child 1
2013-08-08 07:56:26.632 INFO cinder.service [-] wait wrap.failed True

Could you help me, please??