D800 knock on not working anyone help me ?

Hey folks i had try almost everything before create new thread tired with update touch firmware on jb then reflash stock jb firmware also upgrade to KitKat then downgrade to stock but nothing work to knock on screen my proximity sensor just fine working there is not even single issue i didn't find solution for my device which will make knock on back to working

any suggestion guys?

Sent from my LG-D200 using XDA Free mobile app