By default, the COMMAND object is only accessible by TDAdmin users.
You can 'unlock' it by setting the Site Parameter below, but it is not recommended.
From the Site Admin help file:
[ QUOTE ]
If this parameter is set to "Y" (default), only users belonging to the TDAdmin group can use the OTA Command object.
If it is set to "N", any user can use it.
If it is set to "ALL", no users can use it.
For more information, refer to the HP Quality Center Open Test Architecture API Reference.