Unable to Create a new virtual disk drive and add it to an existing virtual machine.

Not able to create new virtual disk and add it to an existing vm.

I tried the script

$VM = Get-SCVirtualMachine -Name "SOME_NAME"; New-SCVirtualDiskDrive -VM $VM -Dynamic -Filename "Test" -SCSI -Size 200 -Bus 0 -LUN 1

I received an error message

"New-SCVirtualDiskDrive : The virtual machine must be in either the Poweroff or Stored state before SCVMM can perform
the specified hardware changes. "

I have turned off the VM from the Hyper-V manager. Any clue?