[libvirt] virsh: Can't create .vmdk virtual disk over vCenter while over ESX it works well

Hello, I am trying to create the virtual disk over "virsh". My target is the ESX server that is a part of the vCenter. That is why I connect to it using the vpx://-like URL. The connection itself is being established correctly. Commands like "list --all", "dumpxml <machine>" "vol-dumpxml <volume>" work perfectly well. What doesn't work for me at the moment is "vol-create --file <xml_file> --pool <my_pool>". I would suspect that I am passing some parameters incorrectly and would be digging more into a documentation but I am getting the following response from the server: | virsh # vol-create --file vadp4.xml --pool "iscsi-esx4-1" error: Failed to create vol from vadp4.xml error: internal error Could not create volume: NotImplemented - Der angeforderte Vorgang wird vom Server nicht implementiert.| I have to admit that the very same command worked if I connect to ESX server directly (using esx://-like URL). My question is if it is planned to implement the virtual disk creation in case of vCentere is involved ? Reagrds