error message "rear-view camera is not available"

Hi, i'm having problem with my CLA180. my reverse camera is not working... giving error message "The rear-view camera is not available" as shown in attached photo.

in the beginning, it happen occasionally and it would restore by itself. but now it didn't work at all. i have done computer check at workshop and they said no alarm trigger.

By any chance if anyone have encounter same problem or have suggestion for solution... really appreciate for the feedback. thank you