[Lynne]

Permissions work such that a Yes always trumps a No. So, if their primary usergroup is Registered Usergroup and that usergroup has Can View Calendar set to Yes, then it will be Yes no matter what the secondary usergroups say. So, you need to set it to No for all Registered users and then set it to Yes only for those you want to allow to view the calendar.

I removed all the default vbulletin code you posted - please see our General Site Rules:

Any copyrighted code snippets should be no more than 10 lines in length, unless approved by a member of Staff.

I really don't know much about changing the calendar.php page since I have never paid much attention to the calendar before (except to finally turn it on on my site a few months ago).