Div element won't resize

I'm following the Adobe Dreamweaver CC Digital Classroom book.  In Chapter 10, I started using Grids.  I'm creating a div.  It is supposed to display a blue border, resize handles, and a tab in the top left corner of the div so that I can resize it.  If it doesn't appear this way at first, I'm supposed to click the Design view button to refresh the layout.  I did that, but I still don't see the resize handles or the tab.  I DO see the blue border but cannot resize it.