Hinge joint won't work

Hi, I was going to make a simple 3D pinball game and I use Hinge Joint for both of the flippers, left and right and use InputName as the keys (a and d). In the projects settings, I set the LFlipper to a and DFlipper to d and input the name I have assigned to the flipper objects. I use this script

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class FlipperController : MonoBehaviour {
 
     public float restPosition = 0;
     public float pressedPosition = 45f;
     public float hitStrength = 10000f;
     public float flipperDampper = 150f;
 
     HingeJoint hinge;
 
     public string inputName;
 
     void Start () {
 
         hinge = GetComponent<HingeJoint>();
         hinge.useSpring = true;
 
     }
 
 
     void Update () {
         JointSpring spring = new JointSpring();
         spring.spring = hitStrength;
         spring.damper = flipperDampper;
 
         // If the buttons (Input) are pressed
         // Input.GetKey (KeyCode.A) && Input.GetKey (KeyCode.D)
         if (Input.GetAxis (inputName) == 1) {
             spring.targetPosition = pressedPosition;
         } else {
             // If the buttons are not press
             spring.targetPosition = restPosition;
         }
 
         hinge.spring = spring;
         hinge.useMotor = true;
     }
 }

and set the left flipper min limit to -45, max 0 and right min 0, max limit to 45. It does not seem to work. I am not sure what has caused this. I am using Unity 5.