No softkeys after screen replacement + no light

Hello IFixit,

I bought a new LCD frame assembly for my Samsung Galaxy S4 I9505.

Screen works fine, but the left + right button on the bottem of the screen are not lit up and not working.

I tried my old flex cable for the buttons. They work and lit up aswell.

My thoughts now: 1. Faulty softkeys flex cable 2. Flex cable is not working on the current version of the phone. My old flex cable is a : DS.HF.R 0.9 D46K is working with the phone. But on my new LCD assembly is a flex cable for the softkeys: DS.HF.R 0.9 D35C.

Going to try a few roms today.