Outlook Calendar doesn’t show free/busy

Using Exchange 5.5, we have created calendars with the names of conference rooms is our company, in the Public Folder so that users can reserve these conference rooms. When they open their calendar to set up a meeting under attendee availability, it shows whether the employees are free or busy, but it shows “no information” for the resources(or the conference room calendars). Microsoft said to reinstall sp4 for exchange which I did and that did not work. Any other suggestions? Thanks in advance for your help.