GPG keys

According to: https://wiki.trinitydesktop.org/Preliminary_Stable_Builds I should do : apt-key adv --keyserver keys.gnupg.net --recv-key A04BE668 In order to get the Debian Stretch version installed. But the message I get when trying this is: Executing: /tmp/apt-key-gpghome.NclvApGG4K/gpg.1.sh --keyserver keys.gnupg.net --recv-key A04BE668 gpg: keyserver receive failed: No keyserver available Any suggestions? cheers anthony -- Sent from my linux system running Debian 9, desktop Trinity R14 This email is plain text, not HTML. Any attachments are either .jpg or .pdf