vdiskmanager illegal operation

We are trying to convert VMs to ESX using:

vmware-vdiskmanager.exe -r physical.vmdk -t 6 -h esxi.sanbarrow.local -u root -f passwordfile

"[datastore1000]/import/target.vmdk"

But it return "-h illegal operation".

We used VMWare Workstation and Fusion (latest version), same message from vdiskmanager.

Any help ?

Thanks !