Hi Alain, that sounds very strange. Frankly it doesn’t make much sense that it would work with marker and brush but not with pencil. Are you sure it is not just a matter of how you set your pencil setting? The minimum and maximum values for the size and opacity should be away from each other to make pressure-change visible. If the min and max are close you will not get any variance in your line – even when pressure is on technically speaking. Sorry of this is obvious to you already. 🙂