DIAGNOSIS Your TV isn't sending the audio signal to the soundbar. Most modern TVs don't automatically switch their audio output to the optical port when you plug something in; you have to tell it to.
FIX Grab your TV remote. 1) Go into your TV's sound or audio settings menu. 2) Look for an option called "Audio Output," "Speakers," or "Sound Output." 3) Change it from "TV Speaker" or "Internal Speaker" to "Optical" or "External Speaker." The exact wording varies by brand, but "Optical" is the key. The Ray should play sound immediately after you save the change.
IF THAT DIDN'T WORK Check the optical cable itself. Make sure the square end is fully plugged into the Ray's port (it clicks when seated) and the TV's port. Also, gently inspect the tip of the cable for any visible red light when the TV is on and set to optical output. No light means the TV isn't sending a signal, confirming the settings issue.
HEADS UP Some TVs have a separate setting to turn off their internal speakers. If you change the output to optical and still hear faint sound from the TV, you might need to find and disable "TV Speaker" in a different sub-menu.