Bob reminded me of another Free/Busy problem that sometimes catches people: you may need to initialize the calendar before the mailbox will publish free/busy if you are using older versions of Exchange. Do this by logging into the resource mailbox with Outlook. Exchange 2007 should display free/busy automatically as soon as the resource is created.

“Today's tip reminded me of a problem (and solution!) that we found here, relating to Resource calendars e.g. for bookable rooms. Our default is to show 12 months' free / busy information for these resources, but staff reported problems where no free / busy information was visible for a Resource.

I eventually found a "work around". This consists of opening each resource directly within Outlook, and then making a dummy Calendar entry for several months in the future. I decided to make a recurring appointment for a time that would not conflict with any real appointments (early on Sunday morning!) every month for the next 12 months. This immediately fixed the problem, and resource free / busy data shows up correctly e.g. in a Group Schedule View of all rooms.

My guess is that the "future calendar" for a resource isn't initialized with free / busy information until the first Calendar entry is created. Note that this only works for me if I log into the resource mailbox directly - booking a dummy meeting from my own Calendar has no effect.”