mks nano robin v3.1 to ts35 v2.0 flat cable extension

Hello to all, I am fairly new here, an am upgrading my old geetech g2spro 3D printer on many issues point, but mainly building a mks nano robin v3.1 into an more sturdy MDF external frome in which the old geetech frame in incomporated making it extremely sturdy. To do so i need to extend the 2 flat cables from the board to the ts35 display. I made my own flat cables from a 10 wire roll of rainbow wires and 10 pin flat cable connectors but something strange is happening. When I use both cables extended, i get a white screen. If I use one extended cable and one original cable it works fine, no matter which of the cables is short and which is long and also which of the 2 (actually 3 as I made an extra) long cables I use. Does anyone have tought on the logic of this issue? Kind greats. I still have to verify each new cables pins, but as it doesn't matter which cable I use I believe there shouldn't be an issue there. additionally, does anyone know where to find the pinout of these connector cables, to check the function of each pins. Kind greats Matthieu

I verified the extended cables and they are all fine, normal continuity, no shorts between the leads. also the extension in not much, standard 0,5m to approx 1m.