Exchange resource calendar permissions not enforced

Hi,

We have a number of resource calendars set up individually but identically through EMC, with no delegates and the resource booking attendant enabled.  The objective is to have the resource calendars viewable but not editable by end users, which would be reviewer access rights.  This is on Exchange Server 2010, by the way.

The issue is that no permissions set via PowerShell or Outlook are actually enforced on these calendars, and all users can edit whatever they wish.  Upon adding a test account (appletest) manually, Powershell output is as follows:

[PS] C:\Windows\system32>set-MailboxFolderPermission 4thfloorexecste2@xxxxxx.com:\Calendar -User appletest -AccessRights reviewer
WARNING: The command completed successfully but no permissions of 'xxxxxx.local/Users/xxxxxx 4th Floor Executive
Suite 2:\Calendar' have been modified.
[PS] C:\Windows\system32>get-mailboxfolderpermission -identity 4thfloorexecste2@xxxxxx.com:\calendar

RunspaceId   : 2ecbe504-e4ed-4fe3-9440-5bf0e395e4b0
FolderName   : Calendar
User         : Default
AccessRights : {Reviewer}
Identity     : Default
IsValid      : True

RunspaceId   : 2ecbe504-e4ed-4fe3-9440-5bf0e395e4b0
FolderName   : Calendar
User         : Anonymous
AccessRights : {None}
Identity     : Anonymous
IsValid      : True

RunspaceId   : 2ecbe504-e4ed-4fe3-9440-5bf0e395e4b0
FolderName   : Calendar
User         : Apple Test
AccessRights : {Reviewer}
Identity     : Apple Test
IsValid      : True

Even after removing all permissions for appletest, that user is still able to create/edit the calendar and other users' items.  This is true of all the resource calendars created and there are too many items on them to delete and start over.  Can anyone explain why these permissions aren't being enforced and how to fix the problem?

Thanks.

Dave

UPDATE:

I also tried adding a security group (allmailboxes) with reviewer access rights, which shows as successful... same problem, users can still edit the calendar.