Windows Volume Manager........via Command line

Hi, I am trying to figure out VM in Windows.  Now, I want to learn how to do it in CLI.  When I got to create a DG, I get this error:

C:\>vxdg -g emc-r5 init Harddisk6 Harddisk7 Harddisk8
Failed to complete the operation...
e5030488:

Thanx in advance for any help.