Use the Quick setup on the web interface to set up the OS4 for cross mode operation.
Make sure you have a valid D-STAR network registration for your callsign for REF030C, otherwise the server won't accept your connection or will only link in read only mode. Also make sure you have a valid DMR ID registration for the TGIF server.
Make sure your transceiver's callsign is set to your exact callsign without any whitespaces or prefixes/suffixes.