player starting with "-s-" flag

This is your problem. The player is starting up "disconnected" from the serial port, and will not take commands from any app over serial (which Empire uses to append/replace/enqueue songs). You should upgrade to the latest version of Hijack, and make sure that you aren't giving the serial port to an app (like gpsapp). The Hijack menu option: "Serial Port Assignment" should be set to the player, not applications.