Why can't I see the contents of my Archived Calendar in Outlook?

Some time ago I archived the majority of my calendar in Outlook 2007. When I recently wanted to open the archive and view the calendar entries I was dissapointed as the archive appeared to be empty. Thanks to James for explaining that I needed to click on the "folder list" icon at the bottom of the screen as illustrated in the following screenshot. After doing so the "Calendar" item was visible and I could browse my archived calendar entries.