Fit fillet - principal workflow unclear

 From:  Lara (MALA)
I want to round edges of a cube with the "fit fillet" tool.
I selected all edges and now I don´t know how to bring the tool to influence the edges to round them.
I placed 10 in the dialog for the diameter and clicked done - nothing happens. Then I tried to initialize the operation by clicking (confusionally) in the viewport and sometimes there is an operation sometimes not.
In the german documentation I did read the fit fillet section but there is nothing about its workflow.
Tipps would be great.

Bye Mala

I´ve got it. The fit fillet diameter was to high for the object.

EDITED: 22 Jul 2012 by MALA