Home key not working properly

[Cobravision]

I have the wifi version, and the home key doesn't go home. Long pressing goes to Google Now and double clicking opens S voice. But single press no longer goes to the home screen. Any idea how to fix this?

EDIT: Don't know what caused it, but the problem was limited to the additional user profile. It worked on the main user profile, and once the user was deleted and re-established, it all started working again.