How can i enable SSAO?

I tried to follow below

Activation
Activate the Ambient Occlusion SSAO panel under the Render tab and set the Render Shadows parameter to AUTO or ON on the Rander > Shadows panel.

and clicked fast preview button

I can't see any AO on my scene

How can I enable it???

Activation
Activate the Ambient Occlusion SSAO panel under the Render tab and set the Render Shadows parameter to AUTO or ON on the Rander > Shadows panel.

You did it right.

How can I enable it???

You also need at least one object that will cast or recieve shadows. So you need to enable Cast ot Recieve Shadows on any object.

Thank you it solved