why is unity Crashing While Instantiating grid at Runtime [on hold]

ok so im following this tutorial about prims maze and everything is correctly coded I followed everything in pretty much the exact same way. the problem is that when i hit the play button unity freezes up and the grid doesn't form. its fine when its just instantiating the x for(int x=0,x

this is the code i used

this is the tutorial i am following

public class GridScript : MonoBehaviour { public Transform CellPrefab; public Vector3 Size;

void start()
{
    CreateGrid ();
}

void CreateGrid(){
    for(int x = 0; x < Size.x;x++){
        for(int z = 0; x < Size.z; z++){
            Instantiate(CellPrefab, new Vector3(x, 0, 0), Quaternion.identity);
        }
    }
}

}

but when I have used this code for a different grid it works perfectly fine public Transform PlatPrefab; public Vector3 Size; public int platX, platY, playZ;

// Use this for initialization void Start () { MakeGrid(); }

// Update is called once per frame void MakeGrid(){

    for (int x = 0; x < Size.x; x++) {
            for (int z = 0; z< Size.z; z++) {

            Instantiate(PlatPrefab, new Vector3(x+platX,platY,z+playZ), Quaternion.identity);
    }
}

}

Unity Grid System

does any one know why this is happening