Hi bolepa,
please check if a headphone adapter plug was "forgotten" in the headphone jack. This would switch off the output signal at the 8-pin jack (to subwoofer).
You can also go to "[Function] - Utility - Config2 - 1 Speaker" and switch from "Headphone Switch" to "On" there. Then the Tyros speaker system will work even if a headphone plug is connected.
If such a plug is NOT the reason for you problem, maybe the Tyros speaker system itself or a cable are defective.
Best regards,
Chris