I cant press the button that activates the "ok Google" option

It's grey and it's not like the other buttons

Perhaps it's not available in your area.

Which device?

I'll leave a link to register so you can communicate here, as a guest account u cant .https://forums.androidcentral.com/sh...d.php?t=409154

Welcome to Android Central! Where's the button that you're trying to use? Show us a screenshot: http://forums.androidcentral.com/gen...d-central.html. You'll have to register first.