Simple checpoint system in 3d racing game - some issues.

If you are using C# Language. Then here is the C# version of CheckPoint and Laps system.

Laps Script

 using UnityEngine;
 using System.Collections;
 
 public class Laps : MonoBehaviour {
     
     // These Static Variables are accessed in "checkpoint" Script
     public Transform[] checkPointArray;
     public static Transform[] checkpointA;
     public static int currentCheckpoint = 0; 
     public static int currentLap = 0; 
     public Vector3 startPos;
     public int Lap;
     
     void  Start ()
     {
         startPos = transform.position;
         currentCheckpoint = 0;
         currentLap = 0; 
 
     }
 
     void  Update ()
     {
         Lap = currentLap;
         checkpointA = checkPointArray;
     }
     
 }

Check Point Script

 using UnityEngine;
 using System.Collections;
 
 public class checkpoint : MonoBehaviour {
     
     void  Start ()
     {
 
     }
     
     void  OnTriggerEnter ( Collider other  )
     {
         //Is it the Player who enters the collider?
         if (!other.CompareTag("Player")) 
             return; //If it's not the player dont continue
         
 
         if (transform == Laps.checkpointA[Laps.currentCheckpoint].transform) 
         {
             //Check so we dont exceed our checkpoint quantity
             if (Laps.currentCheckpoint + 1 < Laps.checkpointA.Length) 
             {
                 //Add to currentLap if currentCheckpoint is 0
                 if(Laps.currentCheckpoint == 0)
                     Laps.currentLap++;
                 Laps.currentCheckpoint++;
             } 
             else 
             {
                 //If we dont have any Checkpoints left, go back to 0
                 Laps.currentCheckpoint = 0;
             }
         }
 
 
     }
 
 }

And Just Follow this tutorial to attach scripts on your Game Objects. Link