Help With NavMesh

I'm making a game for a school project where you have to look at the enemy so he doesn't get to the player but when he does collide with the player, it plays a "GameOver" animation. When I tried to implement NavMesh to the terrain, everything works like the way it did but the collision method doesn't get detected or the animation doesn't play.

Enemy's Code:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.AI;
 using UnityStandardAssets.Characters.FirstPerson;
 
 public class SCPMovement : MonoBehaviour
 {
     public float speed = 1f;
     public Transform target;   //Reference to Player
     private NavMeshAgent agent;
     public bool isGameOver = false;
     private Raycast raycast;
 
     // Use this for initialization
     void Start()
     {
         agent = gameObject.GetComponent<NavMeshAgent>();
         
         raycast = target.GetComponent<Raycast>();
     }
 
     // Update is called once per frame
     void Update()
     {
 
         if (raycast.looking == false)
 
         {
             agent.SetDestination(target.position);
             float step = speed * Time.deltaTime;
             transform.LookAt(target);
             transform.position = Vector3.MoveTowards(transform.position, target.position, step);
         }
 
     }
     void OnCollisionEnter(Collision other)
     {
         
          if(other.gameObject.name == "Player") // creates a condition where if the collidedWith object turns into the gameObject, it will destroy the collidedWith object AM
         {
             print("Destroyed");
             isGameOver = true;
             
             print("Destroyed");
             speed = 0f;
             raycast.looking = true;
             
         }
     }
 }
 

Player's Code:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Raycast : MonoBehaviour {
     public Transform target;
     public bool looking = false;
     CharacterController charCtrl;
     // Use this for initialization
     void Start () {
         charCtrl = GetComponent<CharacterController>();
     }
     
     // Update is called once per frame
     void Update () {
         RaycastHit hit;
         Vector3 p1 = transform.position + charCtrl.center;
         float distanceToObstacle = 0;
 
         // Cast a sphere wrapping character controller 100 meters forward
         // to see if it is about to hit anything.
         if (Physics.SphereCast(p1, charCtrl.height * 4 , transform.forward, out hit, 500) && hit.collider.gameObject.CompareTag("gameObject"))
         {
             looking = true;
             print("Hit!");
             distanceToObstacle = hit.distance;
         }
         else
         {
             looking = false;
         }
     }
 }
 

isGameOver Checking Code:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class GameOverScript : MonoBehaviour {
     Animator anim;
     public SCPMovement scpmovement;
     public FinishZone finished;
     // Use this for initialization
     void Start () {
         anim = GetComponent<Animator>();
        
     }
     
     // Update is called once per frame
     void Update () {
         if (scpmovement.isGameOver == true)
         {
             anim.SetTrigger("GameOver");
         }
     }
 }