Instantiate Objects on Cells created during run time

Hey there, I created a grid:

 using UnityEngine;
 using System.Collections;
 
 public class Grid : MonoBehaviour {
 
     public Transform CellPrefab;
     public Vector3 Size;
     // Use this for initialization
     void Start () {
         CreateGrid ();
     }
     
     // Update is called once per frame
     void CreateGrid () {
         for (int x = 0; x < Size.x; x++) {
                         for (int z = 0; z < Size.z; z++) {
 
                                 Instantiate (CellPrefab, new Vector3 (x, 0, z), Quaternion.identity);
                         }
                 }
 
     }
 }

And I want to create cubes on top of the cells when i click them , therefor i used a raycasthit and the name of the hit object. The Problem i have is that im somehow not able to click on the cells. It works if i use a Plane and try to click on it but not on the cells.

 void Update () {
         if (Input.GetMouseButtonDown (0)) {
             RaycastHit hit;
             Ray ray = cam.ScreenPointToRay(Input.mousePosition);
             Debug.Log("1");
             if (Physics.Raycast(ray, out hit) && hit.transform.name=="Cell"){
                 //Instantiate (CannonPrefab);
                             Debug.Log("hit");
             }
                 }
     }

Im aware that the current script does not actual would spawn each cannon in each cell of the grid but i dont want to go on while i even cant click on the cells.

Does anyone have a clue why it wont work like this?