7 bag tetris not working

its not spawning my code is

 using UnityEngine;
 using System.Collections;
 
 
  string GetRandomTetromino ()
      {
  
          if (IUsed == true && LUsed == true && JUsed == true && OUsed == true && SUsed == true && ZUsed == true && TUsed == true) {
  
              IUsed = false;
              LUsed = false;
              JUsed = false;
              OUsed = false;
              SUsed = false;
              ZUsed = false;
              TUsed = false;
  
          }
  
          int randomTetromino = Random.Range(1, 8);
  
          // This string is used to define the location of the next Tetromino.
          string randomTetrominoName = "Prefabs/J";
  
  
  
          // This switch is used to get a random Tetromino out of 7.
          // NOTE: This needs to be modified to have a 7-bag randomiser later.
          switch (randomTetromino)
          {
  
              case 1:
                  if (TUsed == false) {
                      randomTetrominoName = "Prefabs/T";
                      TUsed = true;
                      
                  }
  
                  break;
  
              case 2:
                  if (SUsed == false) {
                      randomTetrominoName = "Prefabs/S";
                      SUsed = true;
                      
                  }
  
                  break;
  
              case 3:
                  if (LUsed == false) {
                      randomTetrominoName = "Prefabs/L";
                      LUsed = true;
                      
                  }
  
                  break;
  
              case 4:
                  if (JUsed == false) {
                      randomTetrominoName = "Prefabs/J";
                      JUsed = true;
                      
                  }
  
                  break;
  
              case 5:
                  if (IUsed == false) {
                      randomTetrominoName = "Prefabs/I";
                      IUsed = true;
                      
                  }
  
                  break;
  
              case 6:
                  if (ZUsed == false) {
                      randomTetrominoName = "Prefabs/Z";
                      ZUsed = true;
                      
                  }
  
                  break;
  
              case 7:
                  if (OUsed == false) {
                      randomTetrominoName = "Prefabs/O";
                      OUsed = true;
                      
                  }
  
                  break;
              
  
          }
  
          // Return the location of the next Tetromino specified by the switch.
          return randomTetrominoName;
  
      }
      public void spawnNext() {
     // Random Index
 string i = (GameObject)Instantiate(Resources.Load(GetRandomTetromino(), typeof(GameObject)), new Vector2(5.0f, 20.0f), Quaternion.identity);
 
     // Spawn Group at current Position
     
 }
 void Start() {
     // Spawn initial Group
     spawnNext();
 }

i copied from another what is wrong?