Eck-widget are not shown

I am new with Illustrator and use the German version CS6 (16.0). In every tuto I watch, they show the use of Ecken-Widget to round corners. Unfortunately, I can't see any Ecken-widget when I create a form. Also in "Ansicht", the parameter "Ecken-Widget einblenden" doesn't exist. Could it be that this function was not available in the older version? Or is there anything else I should try? Thanks