GUI help !

Hi guys ... This script was suposed to show me a "Level UP!" message when a certain amount of coins was reached ... But idk why it don't works ... can any1 help me ?

Here is my script :

 using UnityEngine;
 using System.Collections;
 
 public class LevelPop : MonoBehaviour {
 
     private int coins = 0;
     public GUISkin levelPopSkin;
     
     
     
     // Use this for initialization
     void Start () {
         
         coins = PlayerPrefs.GetInt("Coins", 0);
         
     }
     
     // Update is called once per frame
     void Update () {
         
     }
     
     void FixedUpdate () {
         PlayerPrefs.SetInt("Coins",coins);
     }
     
     void OnGUI()
     {
         DisplayLevel ();
     }
     
     void DisplayLevel()
     {
         GUI.matrix = Matrix4x4.TRS(Vector3.zero, Quaternion.identity,new Vector3(Screen.width / 480.0f, Screen.height / 320.0f, 1));
         GUI.skin = levelPopSkin;
         Rect coinIconRect = new Rect(200, 150, 32, 32);
         
         //LEVEL SHOW ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         string skillLevel = " ";
         
         if(coins >= 7500){
             StartCoroutine(ShowMessage("LEVEL UP !", 2));
         }
         else if(coins >= 6900){
             StartCoroutine(ShowMessage("LEVEL UP !", 2));
         }
         else if(coins >= 5600){
             StartCoroutine(ShowMessage("LEVEL UP !", 2));
         }
         else if(coins >= 4500){
             StartCoroutine(ShowMessage("LEVEL UP !", 2));
         }
         else if(coins >= 2300){
             StartCoroutine(ShowMessage("LEVEL UP !", 2));
         }
         else if(coins >= 1600){
             StartCoroutine(ShowMessage("LEVEL UP !", 2));
         }
         else if(coins >= 800){
             StartCoroutine(ShowMessage("LEVEL UP !", 2));
         }
         else if(coins >= 400){
             StartCoroutine(ShowMessage("LEVEL UP !", 2));
         }
         else if(coins >= 200){
             StartCoroutine(ShowMessage("LEVEL UP !", 2));
         }
         else if(coins >= 100){
             StartCoroutine(ShowMessage("LEVEL UP !", 2));
         }
         else if(coins >= 0){
             StartCoroutine(ShowMessage("LEVEL UP !", 2));
         }
         
         
         
         
         Rect labelRect = new Rect(coinIconRect.xMax, coinIconRect.y, 60, 32);
         GUI.Label(labelRect, skillLevel);
     }
     
     IEnumerator ShowMessage (string message, float delay) {
         guiText.text = message;
         guiText.enabled = true;
         yield return new WaitForSeconds(delay);
         guiText.enabled = false;
     }
 }