Daf cf 65 auto gearbox issues?

2013 DAF CF65 - auto box problem

we've changed the gearbox for a proper recon unit , we've changed the clutch for a genuine one, we've changed the selector switch. But we keep getting engine warning /gearbox fault light on dash . not all the time , just every 3 or 4 weeks. we have no idea what to do from here