Menambah stok di aplikasi Point Of Sales

Assalamualaikum,.. Berikut Tahapannya :
 

Terima kasih

Assalamualaikum,.. 
sdh saya coba dan ikuti tahapannya tetap gk berubah stoknya..mohon bantuannya
 

Assalamualaikum,.. saya coba input data barang baru juga sama stoknya gk berubah

Assalamualaikum,.. buka file application\models\Model_app.php
pada baris 146 perharikan querynya, semua 'null' pada query ubah menjadi '0', jadi seperti ini :
 
public function stok($id){
return $this->db->query("SELECT (sum(z.jml)-sum(z.kurang)) as stok FROM 
    (SELECT sum(a.jml_terima) as jml, 0 as kurang FROM mu_pembelian_terima_detail a JOIN mu_pembelian_terima b ON a.id_pembelian_terima=b.id_pembelian_terima where a.id_barang='$id' 
    UNION
    SELECT 0 as jml, sum(a.jml_return) as kurang FROM mu_pembelian_return_detail a JOIN mu_pembelian_return b ON a.id_pembelian_return=b.id_pembelian_return where a.id_barang='$id'
    UNION 
    SELECT sum(tambah) as jml, sum(kurang) as kurang FROM mu_penyesuaian_detail where id_barang='$id'
    UNION 
    SELECT 0 as jml, sum(b.jumlah_jual*b.jumlah_satuan) as kurang FROM `mu_transaksi` a JOIN mu_transaksi_detail b ON a.id_transaksi=b.id_transaksi where b.id_barang='$id'
    UNION
    SELECT sum(a.jumlah_return) as jml, 0 as kurang FROM `mu_transaksi_return_detail` a JOIN mu_transaksi_detail b ON a.id_transaksi_detail=b.id_transaksi_detail JOIN mu_transaksi_return c ON a.id_transaksi_return=c.id_transaksi_return where c.status='selesai' AND b.id_barang='$id') as z");
}

Assalamualaikum,.. ok saya coba

Assalamualaikum,.. Alhamdulillah sdh bisa mas...terima kasih banyak

Assalamualaikum,.. 
Saya coba hosting aplikasinya, tapi pada saat launch muncul kayak gambar ini...mohon bantuannya