The scrub/play tool and the preview button doesnt work

Why in the toolbar my scrub/play tool doesn’t work?
Also, following this route: Audio - Plug-ins - (and some effect). When i try to use the preview button, doesnt work.
I already tried with the scrub options on the preferences menu, and by reinstalling everything of Cubase. And i have done all the updates.
Note: The jog/scrub tool of the transport panel does work.
I use Windows 7 64 bits.

Do you use control room?

No, I didn’t do it. How can I use the Control Room to solve those problems?

Make sure it’s deactivated in VST Connections.

Yes, it worked great now! Thank you very much!

So long as a monitor bus is defined in outputs, and marked as default, or “Main Mix” is enough, regardless whether the CR is active or not.