[libvirt] libvirt glusterfs problem

Hi I am running libvirt 1.2.0 on ubuntu. The main purpose of this libvirt 1.2.0 is for glusterfs, now I can define glusterfs storage pool using virsh command, but when I tried to create the volume under the gluster storage pool, I got error. error: Failed to create vol from tt.xml error: this function is not supported by the connection driver: storage pool does not support volume creation. But according to this url http://libvirt.org/storage.html we can create the volume. Any body please help me. Br. Umar