That is correct Paul, groupID 16 is the non-working ID group and is in the 'users' array.
Code:
'users' => array( 2,16 ) , // vBulletin usergroups allowed standard access to chat.
'mods' => array( 5,7 ) , // vBulletin usergroups allowed access as chat moderators.
'admin' => array( 6 ) , // vBulletin usergroups allowed access as chat administrators.
'banned' => array( 1,8 ) , // vBulletin usergroups banned from accessing the chat.
'customer' => array( 0 ) , // vBulletin usergroups allowed access as customers (Live support mode only).