Cannot enable Container registry feature

Hello, I need help to enable the registration of containers in my private gitlab (gitlab-ce v10.6.3), I followed the guide, but when I try to enter the url configured page is blank . Entering as administrator of Gitlab I see that the feature is not enabled. in the logs it says nothing.

I Configure this settings:
registry_external_url ‘
registry_nginx[‘ssl_certificate’] = “/etc/gitlab/ssl/”
registry_nginx[‘ssl_certificate_key’] = “/etc/gitlab/ssl/”

i already have configured gitlab-ce/mattermost and ldap authentication

thanks in advance!