My speedometer is off after converting to Km/h

1) Outer dial ring is changed to km/h (shows up to 330km/h)

2) Computer is set to show km/h (at least km/h is lit up on the white center dial)

3) Dealer says analog scale is lagging digital

Have they missed any coding?

MB central technicians have been contacted by the dealer but can't not provide a solution...

Thanks,

Paul