I'm a beginner , currently i have a problem with sorting order pragramatically .

hello, guys. currently, im doing an assignment of unity website. it's making simple angry birds game. but i have a problem with sorting orders.... the linerenderers's layer orders are not changed.

my codes are below :

using System.Collections; using System; using UnityEngine;

public class ProjectTileDragging : MonoBehaviour {

 //variables for catapult
 public float maxStretch = 3.0f;
 public LineRenderer catapultLineFront;
 public LineRenderer catapultLineBack;

 private SpringJoint2D spring;
 private Transform catapult;
 private Ray rayToMouse;
 private Ray leftCatapultToProjectile;
 private float maxStretchSqr;
 private float circleRadius;
 private Vector2 prevVelocity;
 private bool clickedOn = false;

 //prediction line
 int samples = 15;
 float spacing = 0.1f;
 private GameObject[] line;
 private Vector3 home;
 int force = 4;



 void Awake()
 {
     spring = GetComponent<SpringJoint2D>();
     catapult = spring.connectedBody.transform;
 }

 // Use this for initialization
 void Start()
 {
     LineRendererSetup();
     rayToMouse = new Ray(catapult.position, Vector3.zero);
     leftCatapultToProjectile = new Ray(catapultLineFront.transform.position, Vector3.zero);
     maxStretchSqr = maxStretch * maxStretch;
     CircleCollider2D circle = GetComponent<Collider2D>() as CircleCollider2D;
     circleRadius = circle.radius;

     line = new GameObject[samples];
     for (int i = 0; i < line.Length; i++)
     {
         var go = GameObject.CreatePrimitive(PrimitiveType.Sphere);
         go.GetComponent<Collider>().enabled = false;
         go.transform.localScale = new Vector3(0.2f, 0.2f, 0.2f);
         line[i] = go;
     } 
     home = transform.position;
 }

 void FixedUpdate()
 {

     if (clickedOn)
         DisplayLine();
 }
  
 // Update is called once per frame
 void Update()
 {
     if (clickedOn)
         Dragging();

     if (spring != null)
     {
         if (!GetComponent<Rigidbody2D>().isKinematic && prevVelocity.sqrMagnitude > GetComponent<Rigidbody2D>().velocity.sqrMagnitude)
         {
             Destroy(spring);
             GetComponent<Rigidbody2D>().velocity = prevVelocity;
         }
         if (!clickedOn)
             prevVelocity = GetComponent<Rigidbody2D>().velocity;

         LineRendererUpdate();
     }
     else
     {
         catapultLineFront.enabled = false;
         catapultLineBack.enabled = false;
     }

 }
  
 void LineRendererSetup()
 {
     catapultLineFront.SetPosition(0, catapultLineFront.transform.position);
     catapultLineBack.SetPosition(0, catapultLineBack.transform.position);


     catapultLineFront.sortingLayerName = "ForeGround";
     catapultLineBack.sortingLayerName = "ForeGround";


     catapultLineFront.sortingOrder =6;
     catapultLineBack.sortingOrder = 6;

     Debug.Log("front:" + catapultLineFront.sortingLayerName + "// order = " + catapultLineFront.sortingOrder);
   

 }
 
 void OnMouseDown()
 {
     spring.enabled = false;
     clickedOn = true;
     Debug.Log("ff");
 }

 void OnMouseUp()
 {
     spring.enabled = true;
     GetComponent<Rigidbody2D>().isKinematic = false;
     clickedOn = false;
 }

 void Dragging()
 {
     Vector3 mouseWorldPoint = Camera.main.ScreenToWorldPoint(Input.mousePosition);
     Vector2 catapultToMouse = mouseWorldPoint - catapult.position;

     if (catapultToMouse.sqrMagnitude > maxStretchSqr)
     {
         rayToMouse.direction = catapultToMouse;
         mouseWorldPoint = rayToMouse.GetPoint(maxStretch);
     }

     mouseWorldPoint.z = 0.0f;
     transform.position = mouseWorldPoint;

 }

 void LineRendererUpdate()
 {

     Vector2 catapultToProjectile = transform.position - catapultLineFront.transform.position;
     leftCatapultToProjectile.direction = catapultToProjectile;
     Vector3 holdPoint = leftCatapultToProjectile.GetPoint(catapultToProjectile.magnitude + circleRadius);
     catapultLineFront.SetPosition(1, holdPoint);
     catapultLineBack.SetPosition(1, holdPoint);

 }

 void DisplayLine()
 {
     line[0].transform.position = transform.position;
     Vector3 v3 = transform.position;
     float y = (force * (home - transform.position)).y;
     float t = 0.0f;
     v3.y = 0.0f;

     for (int i = 1; i < line.Length; i++)
     {
         v3 += force * (home - transform.position) * spacing;
         t += spacing;
         v3.y = y * t + 0.5f * Physics2D.gravity.y * t * t + transform.position.y;
         line[i].transform.position = v3;
     }
 }

}

thank you