same script work on capsule but transform problem with turret model

hi guys i have script which i have attached with it with capsule. it works fine the capsule loot at me and fire at me when at specific position but the problem is that when i attached the same script to the imported model of turret gun it rotates upside down here is the image help me guys i dont know what i am missing :

before running

during running this is the problem I I I V

as you can see the turret gun go upside down and stand vertically . it can look at me and rotate where i go and also shoot me but why is it upside down

. using System.Collections; using System.Collections.Generic; using UnityEngine;

public class aiEasy : MonoBehaviour { public GameObject bulletPrefab; public Transform bulletSpawn; private AudioSource gunAudio; public float fireRate = .25f; private float nextFire; private float lastShot=0.0f; public float fireRate2=0.5f;

 public int gunDamage = 1;

 private WaitForSeconds shotDuration = new WaitForSeconds(0.07f);
 public float fpsTargetDistance;//the distnce of our fps controller
 public float enemyLookDistance;//how much enemy will look when we have been seen
 public float attackDistance;
 public float enemyMovementSpeed;
 public float damping;
 
 public Transform fpsTarget;//fps our
   
 Rigidbody theRigidbody;
 Renderer myRender;

 public float delta=5.5f;
 public float speedy =2.0f;

 private Vector3 startPos;

 // Use this for initialization
 void Start () {
     myRender = GetComponent<Renderer>();
     theRigidbody = GetComponent<Rigidbody>();
     gunAudio = GetComponent<AudioSource>();
     startPos = transform.position;
 }
 
 // Update is called once per frame
 void FixedUpdate () {
     
 /*    Vector3 v = startPos;
     v.x += delta * Mathf.Sin (Time.time * speedy);
     transform.position = v;

*/

     fpsTargetDistance = Vector3.Distance (fpsTarget.position,transform.position);
     if (fpsTargetDistance<enemyLookDistance)
     {
         myRender.material.color = Color.yellow;
         lookAtPlayer ();
         //print ("look at player please");
     }
     if (fpsTargetDistance<attackDistance)
     {
         
         myRender.material.color = Color.red;
     //    transform.Translate=0;
         //move after you
 //        attackPlease();

        // print("Attack!!");
         Fire();
     }
     else
     {
         myRender.material.color = Color.blue;
     }
 }
 void lookAtPlayer()
 {
     Quaternion rotation =Quaternion.LookRotation(fpsTarget.position-transform.position);
     transform.rotation = Quaternion.Slerp(transform.rotation,rotation,Time.deltaTime+damping);

 }
 void attackPlease()
 {
     theRigidbody.AddForce(transform.forward*enemyMovementSpeed);//remember to remove this because player follow you 
 }



 void Fire()
 {
     if (Time.time > fireRate2+lastShot) 
     {
         Debug.Log("this is space pressed");
         // Create the Bullet from the Bullet Prefab
         var bullet = (GameObject)Instantiate(bulletPrefab,transform.position,transform.rotation) ;
         string xx = bulletSpawn.position.ToString();
         Debug.Log("thisssss is soawn buller postion"+ xx);
     

         // Add velocity to the bullet

         bullet.GetComponent<Rigidbody>().velocity = bullet.transform.forward * 50;

         // PlayerController newBullet = (PlayerController)(Instantiate(bulletPrefab, bulletSpawn, Quaternion.identity) as GameObject);
         //PlayerController.direction = bulletSpawn.forward;
         lastShot = Time.time;
         // Destroy the bullet after 2 seconds
         Destroy(bullet, 2.0f);
     }



 }

 private IEnumerator ShottEffect(){

     gunAudio.Play ();

     //laserLine.enabled = true;
     yield return shotDuration;
 //    laserLine.enabled = false;

 }



     

}