LineRenderer showing in the inspector but not in the scene ,why?

my code is the next :
void PoneLineas (Vector3 inicio, Vector3 final) {

		var baseObj = new GameObject ();
		var NL = baseObj.AddComponent<LineRenderer> ();
		NL.SetPosition (0,inicio);
		NL.SetPosition (1,final);
		NL.SetWidth (0.5f,0.5f);
	}

and when run it the lines doesnt appear in the scene but in the inspector i get this:

it already loads the vector3 values that the method receives

This renders for me.
I do notice your 2 vector points are close together. Try specifying two distant points as a test.

Also, are you sure your not drawing a shape over your line? If that box is at centre of world then it might be sitting on top of your line’s 2 points.

Finally just try the demo code at Unity - Scripting API: LineRenderer.SetPosition
If your still having an issue