NonDeleteable option in EVPM ini - not so much.

 I'm having a problem with the NonDeletable option in the EVPM ini file.  I'm using the [Folder] section to create a special folder in the root of the mailbox structure and setting NonDeletable = true.  However, people are still able to move the folder to any other folder, like the Inbox, or just delete it.  

I've seen similar post but no solutions to this problem.  

We're using Enterprise Vault 7.5 with SP2 Exchange 2007 SP1

Here's the ini file:

[Directory]
directorycomputername = evaultprod01
sitename = Enterprise Vault Mirant
 
[Filter]
name = filter1
CreateShortcut = true
DeleteOriginal = true
unreadMAIL = true
UseInactivityPeriod = true
InactivityUnits = days
InactivityPeriod = 90

 
[Mailbox]
distinguishedname = all
 
[Folder]
name = \Personal Retention

filtername = filter1
retentioncategory = PersonalRetention

OverrideArchiveLocks = true

NonDeletable = true