set subnet failure

Did some one encountered the same issue? The Vplex mode is VS2, and the detail error messages as below:

VPlexcli:/> set /clusters/cluster-1/cluster-connectivity/port-groups/port-group-0::subnet /clusters/cluster-1/cluster-connectivity/ subnets/cluster-1-SN00

set:    Evaluation of <

        /clusters/cluster-1/cluster-connectivity/subnets/cluster-1-SN00>> failed.

cause:  Failed to update value of 'subnet'.

cause:  Unable to execute firmware command.

cause:  No directors on which to execute command

Thanks in advance!

Feng