My Outlook 2011 for Mac worked fine until almost 2 weeks ago.  Then the calendar data disappeared for no apparent reason.  Today I tried to save a new appointment to my currently blank calendar but I was unable to do so.  I have a MacBook Pro from early 2011 running Mavericks OSx version 10.9.5 SW with an Intel i7 2.2MHz quad core processor and 8 MB of RAM.  Thanks for your help in advance, Dave