How to activate backlight when turning the wrist in Fenix 5

Hi there,

I just bought a Fenix 5 this afternoon and took it for a run. However, the backlight did not turn on when I turned the wrist so I have to keep on pressing the top left (Light) button whenever I want to see the readings on the watch. This is very troublesome

I did Settings, System, Backlight, and set Gesture = ON but still didn't work.

Any ideas and tip ?

Thanks