I am speculating but I believe this is a fiber optic cable that has to do with the flash control. Make sure it is seated all the way down into the white plastic tube (not the metal clip in front of it). Also if you are repairing a damaged top there could be a piece of the old cable down in the hole as was the case for me and you will have to remove it before putting the new top on. I have pictures but don't see any way I can attach them here.