compare directories

I am trying to use the compare feature but it seems to me it's not working unless I am missing something. After hitting the compare button the right panel becomes gray but nothing happens after that. Does anyone know what is the next step? thanks
Gregoz

There's no next step. Panel becomes grey, because its files become selected (they are new or modified compared with other panel) and the panel is not selected itself (so selection is grey, otherwise it would be blue, but both depends on your Windows theme).