docky: how to enable zoom effect

Dear all,

I'm running a clean januty with gnome do version 8.1.3.

I've enabled Docky view under Preference --> Appearance and flagged animated window

I've tried several combination but I can't be able to enable zoom effect whne you mobve the mouse on the different icon.

compiz is running great and on the sistem it's installed a Ati card.

I feel relly stupid but do you have and idea?

Thank you

L.