Marketplace Multi Seller Multi Buyer v.2.0 - Codeigniter 3.x + Reseller System, API Rajaongkir + COD

Assalamualaikum,.. pada baris 2951 ubah dari 
$this->model_app->insert('rb_produk',$data); 
menjadi 
$this->model_app->insert('rb_rekening',$data);

Assalamualaikum,..  buka file application/controllers/Administrator.php menggunakan editor dan lakukan langkah di atas

Assalamualaikum,.. 
 
setelah dirumah sesuai arahan muncul 
 
An uncaught Exception was encountered
Type: Error
 
Message: Call to a member function rekening_tambah() on null
 
Filename: E:\xampp\htdocs\marketplace\application\controllers\Administrator.php
 
Line Number: 2947
 
Backtrace:
 
File: E:\xampp\htdocs\marketplace\index.php
Line: 294
Function: require_once

Assalamualaikum,.. 
 
setelah sesuai arahan yang diberikan tetap muncul muncul 
 
An uncaught Exception was encountered
Type: Error
 
Message: Call to a member function rekening_tambah() on null
 
Filename: E:\xampp\htdocs\marketplace\application\controllers\Administrator.php
 
Line Number: 2947
 
Backtrace:
 
File: E:\xampp\htdocs\marketplace\index.php
Line: 294
Function: require_once

Assalamualaikum,.. yg baris $this->model_rekening->rekening_tambah(); di hapus saja