Child safety both rear doors, Model GP1

Dear community, yesterday it was time! I finally bought my dream car after I had felt 100 vehicles tested in the last weeks and then decided. A Phaeton year 2007 (model GP1) 3.0 TDI. So far everything with the car is really tip top, even with the mileage of 195tkm it purrs like on the first day and is still very well maintained, but I don’t get the child protection deactivated. Have already looked into the board book and followed the steps, driver door the two buttons glow yellow, if I press them but nothing happens. Is it perhaps because in the board computer something is set? or even that I use the 2nd key (looks brand new)? I can’t imagine the latter. Wouldn’t be nice if anyone could help me. PS: Yes, I used the search function but did not find the same topic, if I am blind now already excused. Lg, MrComposer