Exchange Server 2010 Room Mailboxes Double Booking

We are have several room mailboxes setup on Exchange Server 2010 and are having an issue with rooms being double booked.

I have "Allow Conflicting Meeting Requests" unchecked on the Resource Policy Tab but if a user try's to book a room that is already reserved it gets accepted and put on the calendar.

How do I stop this from happening?

Here are the settings for the room:

AutomateProcessing                  : AutoAccept
AllowConflicts                      : False
BookingWindowInDays                 : 365
MaximumDurationInMinutes            : 1440
AllowRecurringMeetings              : True
EnforceSchedulingHorizon            : True
ScheduleOnlyDuringWorkHours         : False
ConflictPercentageAllowed           : 0
MaximumConflictInstances            : 0
ForwardRequestsToDelegates          : True
DeleteAttachments                   : True
DeleteComments                      : False
RemovePrivateProperty               : True
DeleteSubject                       : False
AddOrganizerToSubject               : True
DeleteNonCalendarItems              : True
TentativePendingApproval            : True
EnableResponseDetails               : True
OrganizerInfo                       : True
ResourceDelegates                   : {}
RequestOutOfPolicy                  : {}
AllRequestOutOfPolicy               : False
BookInPolicy                        : {}
AllBookInPolicy                     : True
RequestInPolicy                     : {}
AllRequestInPolicy                  : False
AddAdditionalResponse               : False
AdditionalResponse                  :
RemoveOldMeetingMessages            : True
AddNewRequestsTentatively           : True
ProcessExternalMeetingMessages      : False
RemoveForwardedMeetingNotifications : False
MailboxOwnerId                      : gsc.local/Users/Board Room
Identity                            : gsc.local/Users/Board Room
IsValid                             : True