Openstack Horizon: Logout user session from Identity Brokering

I’m using Federation Openstack Keystone with Keycloak
I hit the sign out button from openstack dashboard but when I hit sign in again it automatically sign in and not go to authenticate site (Keycloak).
I’m trying Keycloak single sign out like this Keycloak Single Sign Out - but it doesn’t work
How can I solve this problem? Thanks.