Cara buat perintah update_batch pada codeigniter

Assalamualaikum Warahmatullahi Wabarakatuh...
selamat pagi pak, saya lagi bikin perintah update_batch dengan model seperti ini :
 
    public function update_multi($table, $data, $where){
        return $this->db->update_batch($table, $data, $where);
    }
 
dengan controller :
 
function ubah_usulan_kegiatan(){
    cek_session_akses('ubah_usulan_kegiatan',$this->session->id_session);
    $a = $this->uri->segment(3);
 
    if (isset($_POST['submit'])){
  $data2 = array(
        'kd_usulan'=>$this->db->escape_str($this->input->post('a')),
            'x'=> $this->db->escape_str($this->input->post('x[]')),
            'y'=> $this->db->escape_str($this->input->post('y[]')),
            'username'=>$this->session->username);
       $where2 = array('kd_usulan' => $this->input->post('a'));
       $new_values = array();
 
         for($x = 0, $size = count($data2['x']); $x < $size; $x++) {
            foreach($data2 as $key => &$value) {
                if(!is_array($value) || empty($value)) {
                    $new_values[$x][$key] = $value;
                } else {
                    $new_values[$x][$key] = array_shift($value);
                }
            }
 
        }
  $this->model_app->update_multi('ref_tbl_kordinat',$new_values,$where2);
       redirect('administrator/usulan');
}else{
    if($this->session->level=='admin'){
$proses = $this->model_app->edit('tbl_usulan', array('no_urut' => $a))->row_array();
$proses31 = $this->model_app->view_ordering('ref_tbl_kordinat','kd_usulan','DESC');
}else{
       $proses = $this->model_app->edit('tbl_usulan', array('no_urut' => $a, 'username'=>$this->session->username))->row_array();
       $proses31 = $this->model_app->view_ordering('ref_tbl_kordinat','kd_usulan','DESC');
 }
   $data = array('rows' => $proses,'proses31'=>$proses31);
   $this->template->load('administrator/template','administrator/form_usulan/view_edit_usulan',$data);
}
}
 
dengan output errornya seperti ini
 
Array ( [0] => Array ( [kd_usulan] => 1 [x] => 1.00 [y] => 2.00 [username] => admin ) [1] => Array ( [kd_usulan] => 1 [x] => 1.00 [y] => 2.00 [username] => admin ) [2] => Array ( [kd_usulan] => 1 [x] => 1.00 [y] => 2.00 [username] => admin ) )
A Database Error Occurred
 
One or more rows submitted for batch updating is missing the specified index.
 
Filename: C:/xampp/htdocs/febri/system/database/DB_query_builder.php
 
Line Number: 2028
 
mohon bantuannya....gan