get-esxcli V2, esxcli.storage.vmfs.unmap, "does not contain a method named 'unmap'"

PSVersion                      6.0.2

VMware.PowerCLI        10.1.0.8403314

>$esxcli = Get-EsxCli -VMHost "host1" -V2

>$ds = Get-VMHost "host1" | Get-Datastore | select -first 1

>$esxcli.storage.vmfs.unmap("4000",$ds,$null)

Method invocation failed because [VMware.VimAutomation.ViCore.Impl.V1.EsxCli.EsxCliElementImpl] does not contain a method named 'unmap'.

At line:1 char:1

+ $esxcli.storage.vmfs.unmap("4000",$ds,$null)

+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

+ CategoryInfo          : InvalidOperation: (unmap:String) [], RuntimeException

+ FullyQualifiedErrorId : MethodNotFound

Without -V2, it running no errors. Why?

LucD