hit.gameObject.AddComponent not working

Hi,

I would like to add a configurable joint to the rigidbody that the raycast is hitting but when I type hit.gameObject.AddComponent ... it doesn't recognize the statement. What am I doing wrong ?

My code :

 void Update() {
 
         if(Input.GetMouseButtonDown (1)){
         
             Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
             RaycastHit hit;
 
             if (Physics.Raycast(ray, out hit, 100)){
                 Debug.DrawLine(ray.origin, hit.point, Color.cyan);
 
                 if(hit.rigidbody != null){
 
                     ConfigurableJoint joint = hit.gameObject.AddComponent<ConfigurableJoint>();
                     joint.xMotion = ConfigurableJointMotion.Locked;
                     joint.yMotion = ConfigurableJointMotion.Locked;
                     joint.zMotion = ConfigurableJointMotion.Locked;
                     joint.angularXMotion = ConfigurableJointMotion.Free;
                     joint.angularYMotion = ConfigurableJointMotion.Locked;
                     joint.angularZMotion = ConfigurableJointMotion.Locked;
                     joint.angularXDrive = new JointDrive
                     {
                         mode = JointDriveMode.Velocity,
                         maximumForce = 10f,
                         positionDamper = 0f,
                         positionSpring = 0f
                     };
                     joint.breakForce = 20;
                     joint.breakTorque = 10;
                     joint.enableCollision = true;
 
                 }
             }
         }
     }