Adjusting MAN TGS Exhaust Brake

Hi all,
On my MAN TGS 2014 the exhaust brake only comes on when you dive on the brakes really hard. I assume it should come on when just resting on the brake pedal? How do you adjust this?
Cheers,
Nick

You should be able to apply the exhauster without touching the brakes at all by pressing the button on the end of the RH column stalk, if an auto it should automatically select the best gear for maximum engine braking, all this regardless of footbrake used or not.

The auto exhauster switch on the lower bank of switches is turned on?