Nova can't spawn new instance with "virDomain instance has no attribute 'createWithFlags'" error on RHEL6.0

# virsh list --all
 Id Name State
----------------------------------

# source novarc
# euca-run-instances ami-2a835aae --kernel aki-34cf3629 --ramdisk ari-217d77df -k rhelkey -t m1.tiny
RESERVATION r-i9nxdcy8 rhelimg default
INSTANCE i-00000001 ami-2a835aae scheduling rhelkey (rhelimg, None) 0 m1.tiny 2011-04-11T08:52:49Z unknown zone

2011-04-11 12:52:51,544 nova.virt.libvirt_conn: instance instance-00000001: Creating image
2011-04-11 12:52:51,641 nova.utils: Attempting to grab semaphore "34cf3629" for method "call_if_not_exists"...
2011-04-11 12:52:51,656 nova.utils: Running cmd (subprocess): cp /var/lib/nova/instances/_base/34cf3629 /var/lib/nova/instances/instance-00000001/kernel
2011-04-11 12:52:51,693 nova.utils: Attempting to grab semaphore "217d77df" for method "call_if_not_exists"...
2011-04-11 12:52:51,707 nova.utils: Running cmd (subprocess): cp /var/lib/nova/instances/_base/217d77df /var/lib/nova/instances/instance-00000001/ramdisk
2011-04-11 12:52:51,759 nova.utils: Attempting to grab semaphore "2a835aae_sm" for method "call_if_not_exists"...
2011-04-11 12:52:52,024 nova.utils: Running cmd (subprocess): qemu-img create -f qcow2 -o cluster_size=2M,backing_file=/var/lib/nova/instances/_base/2a835aae_sm /var/lib/nova/instances/instance-00000001/disk
2011-04-11 12:52:52,064 nova.virt.libvirt_conn: instance instance-00000001: injecting key into image 713251502
2011-04-11 12:52:52,081 nova.compute.disk: Mounting disk...
2011-04-11 12:52:56,717 nova.compute.disk: Injecting SSH key...
2011-04-11 12:52:57,474 nova.compute.disk: Deleting guestfs object...
2011-04-11 12:52:59,280 nova.exception: Uncaught exception
(nova.exception): TRACE: Traceback (most recent call last):
(nova.exception): TRACE: File "/usr/lib/python2.6/site-packages/nova/exception.py", line 120, in _wrap
(nova.exception): TRACE: return f(*args, **kw)
(nova.exception): TRACE: File "/usr/lib/python2.6/site-packages/nova/virt/libvirt_conn.py", line 611, in spawn
(nova.exception): TRACE: domain = self._create_new_domain(xml)
(nova.exception): TRACE: File "/usr/lib/python2.6/site-packages/nova/virt/libvirt_conn.py", line 1072, in _create_new_domain
(nova.exception): TRACE: domain.createWithFlags(launch_flags)
(nova.exception): TRACE: AttributeError: virDomain instance has no attribute 'createWithFlags'
(nova.exception): TRACE:
2011-04-11 12:52:59,281 nova.compute.manager: ERROR [WYUWXZ5CBTCE7-NTFUKK abr rhelimg] Instance '1' failed to spawn. Is virtualization enabled in the BIOS?
(nova.compute.manager): TRACE: Traceback (most recent call last):
(nova.compute.manager): TRACE: File "/usr/lib/python2.6/site-packages/nova/compute/manager.py", line 234, in run_instance
(nova.compute.manager): TRACE: self.driver.spawn(instance_ref)
(nova.compute.manager): TRACE: File "/usr/lib/python2.6/site-packages/nova/exception.py", line 126, in _wrap
(nova.compute.manager): TRACE: raise Error(str(e))
(nova.compute.manager): TRACE: Error: virDomain instance has no attribute 'createWithFlags'
(nova.compute.manager): TRACE:
2011-04-11 12:53:39,710 nova.compute.manager: Found instance 'instance-00000001' in DB but no VM. State=5, so setting state to shutoff.
2011-04-11 12:54:39,742 nova.compute.manager: Found instance 'instance-00000001' in DB but no VM. State=5, so setting state to shutoff.