Pick up and Time delay problems

I tried to add a time delay to my code and make it wait a few seconds before moving onto the next level. But now with the new code, I am unable to pick up the object. Please help.

 void Start ()
     {
         count = 0;
         levelNumber = 1;
         winText.text = "";
         
     }
     
     
     void OnTriggeEnter(Collider other)
     {
         if(other.gameObject.tag == "PickUp")
         {
             other.gameObject.SetActive(false);
             AddCount(1);
         }
     }
     
     void AddCount(int val)
     {
         count += val;
         countText.text = "Count: " + count.ToString();
         
         if(count >= 1)
         {
             FinishLevel();
         }
     }
     
     void FinishLevel()
     {
         levelNumber = levelNumber + 1;
         winText.text = "CONGRAGULATIONS!";
         
         Invoke("LoadNextLevel", 3);
     }
     
     void LoadNextLevel()
     {
         Debug.Log ("Level Number: " + levelNumber);
         Application.LoadLevelAsync(Application.loadedLevel + 1);
     }
 }