Hinge Joint via script not working

Hi guys, I have a project (attached, only 120 kb) in which I have a sphere (MenuNode) that creates another five spheres.

I want these five created spheres follow the main sphere (that who creates).

I did that using the Hinge Joint in the editor, but now I want to make it work via script.

Do you see something wrong with this code?

Thats the code:

 using UnityEngine;
 using System.Collections;
 
 public class MenuNodeController : MonoBehaviour {    
     
     //it's all public :)
     public MenuNodeController prefab;
     public bool isSubNode;
     public Vector3 screenPoint;
     public Vector3 offset;
     public Vector3 startPoint;
     public Vector3 endPoint;
     public float startTime;
     public float duration;    
     public static bool touched;    
     
     void Start () {
         
     }
         
     void Update () {
         if (isSubNode) {
             this.transform.position = Vector3.Lerp(startPoint, endPoint, (Time.time - startTime) / duration);
         }
         
         if (Input.GetMouseButtonDown(0)) {
             RaycastHit hit = new RaycastHit();
             Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
             if (Physics.Raycast(ray, out hit)) {    
                 if (!touched) {
                     for (int i = 0; i < 5; i++) {
                         touched = true;
                     
                         MenuNodeController subNode = (MenuNodeController)Instantiate(prefab);
                     
                         subNode.rigidbody.isKinematic = false;
                         subNode.rigidbody.useGravity = false;
                                         
                         subNode.isSubNode = true;
                         subNode.startTime = Time.time;
                         Vector3 endPosition = new Vector3(x(25 * i), y(25 * i), 0);
                         subNode.endPoint = endPosition;
                         subNode.startPoint = this.transform.position;
                         subNode.duration = 2;                        
                         
                         HingeJoint joint = this.gameObject.AddComponent<HingeJoint>();
                         joint.connectedBody = subNode.rigidbody;
                         
                         this.rigidbody.isKinematic = true;
                         this.rigidbody.useGravity = false;                                    
                     }
                 }
             }
         }                        
     }
     
     void OnMouseDown() {
        screenPoint = Camera.main.WorldToScreenPoint(gameObject.transform.position);
        offset = gameObject.transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z)); 
     }
     
     void OnMouseDrag() {        
         Vector3 curScreenPoint = new Vector3(Input.mousePosition.x, Input.mousePosition.y, screenPoint.z);
         Vector3 curPosition = Camera.main.ScreenToWorldPoint(curScreenPoint);
         transform.position = curPosition;
     }
     
     float x(double a) {
         float xa = (float) (Mathf.PI * a/180.0f);
         return 5 * Mathf.Cos(xa);
     }
     
     float y(double a) {
         float ya = (float) (Mathf.PI * a/180.0f);
         return 5 * Mathf.Sin(ya);
     }
 }

The whole project is attached, in this project the hinge joint works when did in the editor.