Reverse Camera

[SteveF20Yeah]

Hi could anyone help me with this issue, I have a F20 pre LCI 120D manual, when I brought it it had aftermarket reverse sensors and no reverse camera. it had a CIC head unit fitted as standard. I added an android/ apple carplay box from Bavarian automotive which basically wired in between the screen and the CIC. I noticed that when I put the car into reverse it would bring up the reverse camera but obviously said "No signal" due to not having one fitted.     

As the android/ apple carplay box had a yellow video in plug I decided to add a aftermarket reverse camera which worked perfectly.

I have since had the CIC upgraded to the NBT Professional and have installed the full vibe Optisound speaker kit, removed the android/ apple carplay box and replaced the tiny OEM screen with a bigger Bavarian automotive andriod screen. I connected the reverse camera to the new screen as that also had a yellow video input but now when I put the car in reverse the screen does not change and the camera does not work. 

I have added code 3AG and this hasn't worked, i flashed the code into NBT and REM module. Can anyone point me in the wright direction?

Its either a coding issue and I need to add another or additional codes or a wiring issue as the new vibe amplifier intercepts the loom as it is a oem upgrade kit, could the reverse signal not be reaching the NBT unit? 

Thanks All,