Yes, I mean this, it should not be blank, and I suppose, that you haven't installed any calendar yet.
So, in the left down quarter of KOrganizer, you can (must) add a new calendar with right click at that location.
Try it, you will receive a menue then with entry 'Add calendar'. Select it and then choose 'std.ics'.
Then you have your own calendar.
It is also possible (though difficult) to add a synchronized Google calendar also.
But to add a simple calendar, pls follow the way I told you above...
-Linuxfluesterer (I love KDE ...)