Airbrush Soft Grainy - not acting as expected

Hello everyone,

I am experiencing some difficulties using this brush called Airbrush Soft High Density Grainy, that i was able to get by downloading the Legacy brushes pack in Photoshop version 25.5.1.

I recently watched a video demo of this brush and the result wanted is much more different that what it actually does when I try it. It appears only as a grainy round flat stroke, not that 'gradient' texture fade i want to achieve. 

Also the stroke it creates on the canvas is way different that the stroke preview I see in the brush panel.

I am using a wacom Pen & Touch tablet. I tried messing with the settings a little, but nothing seems to work and fix it.