OK so I figured it out, mine was doing it too. You should be able to drag the box that says "no event" into that little side bar menu there. Just tap the arrow to bring it out, then drag the box over to it. You should be all set :)
I went into the widget and deselected the calendar and it went away, however I'm not sure how to explain why it worked.
Mine is doing the same thing and I have not figured it out yet! Good Luck. I'll keep looking.