What was found
CABIN EMERG LIGHT: TESTED NORMAL FIRST FLIGHT OF DAY YESTERDAY AND TODAY. WHILE IN MDW, ANOTHER LATITUDE CAPTAIN ASKED IF HE COULD CHECK EMER LIGHTS TO COMPARE BRIGHTNESS, WHICH I COMPLIED WITH. HE TURNED OUR EMER LIGHTS SWITCH ON AND NOTHING ILLUMINATED. I TRIED IT MYSELF AND SAME EFFECT. I CONTACTED MX AND HE ASKED ME TO ATTEMPT W2 POWER DOWN, WHICH I DID, AND AGAIN NO ILLUMINATION OF ANY LIGHTS.