[keycloak-user] Consistent error Unknown Saml Response when trying to log in through remote IDP

Hi, I have set up a test environment with a remote IDP (simplesamlphp) for Keycloak (1.6.1 Final). When I try to use the remote IDP to log in, I always get a "We're sorry, invalid request" page. SamlService.handleResponse(), where a cookie named KEYCLOAK_IDENTITY is expected to exist and be valid, which never seems the case. I have experimented with different configuration options for the remote IDP, but nothing changes this. Can anyone shed some light on this? Thanks. -- Regards, Ton