On being Invoked by KeyPress, my gameobject appears alright, but does not get invoked again on key press?

Question

I was instantiating and destroying my gameobjects earlier but on learning that it is processor intensive, manipulated my code so that it is an object pool of 1 object. When I press Z, my object gets activated and starts scaling bigger as long as Z is pressed, and on key up, it deactivates the object, but when Z is pressed again, the object doesn't get Invoked again. What am I doing wrong ?

float speed = 2f;
public GameObject radius;
public int pooledAmount = 1;
List<GameObject> radiusorb;

void Start(){

   radiusorb = new List<GameObject> ();
   for (int i = 0; i < pooledAmount; i++)
   {
     GameObject obj = (GameObject)Instantiate (radius);
     obj.SetActive(false);
     radiusorb.Add (obj);
   }
}

void Update (){
   if(Input.GetKeyDown(KeyCode.Z))
   {
     Invoke("LetRadiusExist",0.001f);        //Instantiating the prefab
      }

   if (Input.GetKey(KeyCode.Z)) {              //Scale the object
     if (gameObject != null)
     {
      gameObject.transform.localScale += gameObject.transform.localScale * (Time.deltaTime * speed);
     }
   }

   if(Input.GetKeyUp(KeyCode.Z))               //To deactivate the prefab
   {
     gameObject.SetActive(false);

     //Destroy(cloneRadius, 0);
   }
}

void LetRadiusExist()
{
   for (int i = 0; i < radiusorb.Count; i++) 
   {
     if (!radiusorb[i].activeInHierarchy)
     {
      radiusorb[i].SetActive(true);
      radiusorb[i].transform.parent = transform;
      radiusorb[i].transform.localPosition = new Vector3(0,0,0);
      break;
     }

   }
}

Answer 1

You are changing your actual game object instead of the radius object that you have pooled. So when the Z key is released, you are deactivating your game object and then no further processing is done.

Also you actually don't need a list, since you are using one object only. So this can be simplified a lot:

float speed = 2f;
public GameObject radiusPrefab;

// your "pooled" instance.
private GameObject instance;

void Start(){
   instance = (GameObject)Instantiate (radiusPrefab);
   instance.SetActive(false);
}

void Update (){
   if(Input.GetKeyDown(KeyCode.Z))
   {
       instance.SetActive(true);
   }

   if (Input.GetKey(KeyCode.Z)) {              //Scale the object
      instance.transform.localScale += instance.transform.localScale * (Time.deltaTime * speed);
   }

   if(Input.GetKeyUp(KeyCode.Z))               //To deactivate the prefab
   {
      // make sure to reset the scale!
      instance.transform.localScale = Vector3.one;
      instance.SetActive(false);
   }
}