The shadows in your drawing differ too much from the "normal" lines. They look like a different entity instead of being part of the whole.
From what I know of this style of shading, the shadows are drawn with the same type of pen as the outlines, like a sharpie, an actual ink pen or even a fine brush dipped in ink. The outlines gradually get thicker from the light areas to the shadows. How thick they'll be in the end depends on how much you want to emphasize the shadow, but at the transition between lit and shaded area, they shouldn't be much thicker than the normal lines.
You can watch an artist create and explain shading by line weight in this video.
Also keep in mind where your light source is. In your first example the thick lines are all over the place and it's hard to recognize them as shadows at all. The places where those thick lines are don't seem to be realistic places for shadows. The second example is much better because you emphasized the shadow on the stomach that is cast by the arm and the shadow at the hips that is cast by the clothing.
But the shadow at the back of the shoulder is wrong there. The arm and clothing cast shadows as if the light comes from directly above the person. That means the soulder should be very bright, because it's very close to the light source. The shadows you drew on the shoulder indicate that the light source is at eye level in front of the person instead.