Error models Manggaleh - Unknown column 'b.ppn' in 'field list'

Assalam,.. buka file "application/models/model_laporan.php"
cari public function view_pelanggan_tersering() dan ubah semuanya menjadi seperti ini :
 
public function view_pelanggan_tersering(){
return $this->db->query("select a.nama_pelanggan, a.alamat_pelanggan_1, a.kota, b.trx, c.total from
                            (select x.*, y.name as kota from mu_pelanggan x JOIN mu_city y ON x.city_id=y.city_id) as a 
                            LEFT JOIN
                            (select id_pelanggan, COUNT(*) trx from mu_transaksi GROUP BY id_pelanggan HAVING COUNT(id_pelanggan)) as b on a.id_pelanggan=b.id_pelanggan
                            LEFT JOIN
                            (SELECT a.*, b.id_pelanggan, sum(a.jumlah_jual*a.jumlah_satuan*a.harga_jual-a.diskon_jual) as total FROM `mu_transaksi_detail` a JOIN mu_transaksi b ON a.id_transaksi=b.id_transaksi GROUP BY b.id_pelanggan) as c on a.id_pelanggan=c.id_pelanggan where b.trx >=1 ORDER BY b.trx DESC");
}

Assalam,.. thanks gan,..Successfully