Pay close attention to the angle the needle enters the skin. It MUST penetrate the skin at a 90-degree angle when performing the hair stroke technique.
It is important to note that the ombre technique requires your needle to enter the skin at a 45-degree angle. This is because it is important to slowly build up your shading as you work on the skin, thus creating a soft powdered pixelated finish. By entering the skin on a 45-degree angle, you will penetrate the skin on a shallower level, allowing you to build a soft shadow.
See picture below of the ombre technique. As you can see the front of the brow is lighter and the mid to tail of the brow blends to a darker tone.