i9300 S3 return and menu button – pcb ok, lcd flex?

1. Sorry for my english 😉
2. I change glass in i9300 and i have a problem with return and menu buttons, they not work. PCB is ok (with other lcd return and menu ok). Flex with buttons is ok (i check on 3 flex’s). I think problem is in LCD flex. Have you any schemat or sugestions?