Live Snapshot with PVE 2.3-6 qmp command 'snapshot-drive' failed - Not supported

Live Snapshot with PVE 2.3-6
not working when done from GUI
with following error :

qmp command 'snapshot-drive' failed - Not supported

More details :
Output of error message
VM 104 qmp command 'snapshot-drive' failed - Not supported


MORE INFO ABOUT SUSTEM AND CONFIG :

root@proxmox:~# qm config 104
boot: cdn
bootdisk: virtio0
cores: 1
ide2: none,media=cdrom
memory: 2048
name: netflow
net0: rtl8139=00:0C:29:33:AC:64,bridge=vmbr0
ostype: l26
sockets: 1
virtio0: local:104/vm-104-disk-2.qcow2,size=20G

root@proxmox:~# cat /etc/pve/storage.cfg
nfs: Synology
path /mnt/pve/Synology
server 10.10.10.38
export /volume1/NetBackup
options vers=3
content backup
maxfiles 10


dir: local
path /var/lib/vz
content images,iso,vztmpl,rootdir
maxfiles 0


dir: disk_backup
path /disk_backup
content images,iso,vztmpl,rootdir,backup
maxfiles 2

root@proxmox:~# pveversion -v
pve-manager: 2.3-6 (pve-manager/2.3/bcbdbcc8)
running kernel: 2.6.32-16-pve
proxmox-ve-2.6.32: 2.2-82
pve-kernel-2.6.32-16-pve: 2.6.32-82
lvm2: 2.02.95-1pve2
clvm: 2.02.95-1pve2
corosync-pve: 1.4.4-4
openais-pve: 1.1.4-2
libqb: 0.10.1-2
redhat-cluster-pve: 3.1.93-2
resource-agents-pve: 3.9.2-3
fence-agents-pve: 3.1.9-1
pve-cluster: 1.0-36
qemu-server: 2.3-8
pve-firmware: 1.0-21
libpve-common-perl: 1.0-44
libpve-access-control: 1.0-25
libpve-storage-perl: 2.3-2
vncterm: 1.0-3
vzctl: 4.0-1pve2
vzprocps: 2.0.11-2
vzquota: 3.1-1
pve-qemu-kvm: 1.3-17
ksm-control-daemon: 1.1-1



cat /var/log/pve/tasks/index
UPID:proxmox:0001B83F:00110E6B:5108D3AC:stopall::r oot@pam: 5108D3BB OK
UPID:proxmox:00000970:00000E74:5108D446:startall:: root@pam: 5108D446 OK
UPID:proxmox:0000142E:000061B3:5108D51C:qmstart:10 4:root@pam: 5108D51D OK
UPID:proxmox:00001C8A:0000B014:5108D5E4:qmsnapshot :104:root@pam: 5108D5FB VM 104 qmp command 'snapshot-drive' failed - Not supported



Please Help to SOLVE this

Thanks in ADVANCE