Scania tachograph display on dash not working

I’m driving a 2016 Scania with a Stonebridge duo exact tachograph fitted. For some reason the tachograph information display on the dashboard is constantly blank, no times being shown. Any one know what might be up with it?

I always…

Assumed the all Skarniarse tachos worked in that manner.

Should be done on pre delivery inspection some of ours don’t work but most do . One of our drivers took it into Scania said it was a 5 minute job to sort out .

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