private void TXT_QTY_KeyDown(object sender, KeyEventArgs e)
 {
     if (e.KeyCode == Keys.Enter)
     {
         TXT_COST.Focus();
     }
 }
 private void BTN_ADD_Click(object sender, EventArgs e)
 {
     if (ITEM_CODE == String.Empty)
     {
         TXT_QTY.Focus();
         MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE SELECT ITEM!", MessageAlertImage.Alert());
         mdg.ShowDialog();
     }
     else if (Convert.ToDouble(TXT_QTY.Text) <= 0)
     {
         TXT_QTY.Focus();
         MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE ENTER QTY!", MessageAlertImage.Alert());
         mdg.ShowDialog();
     }
     else if (Convert.ToDouble(TXT_COST.Text) <= 0)
     {
         TXT_COST.Focus();
         MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE ENTER COST PRICE!", MessageAlertImage.Alert());
         mdg.ShowDialog();
     }
     //else if(Convert.ToDouble(TXT_SALE.Text) <= 0)
     //{
     //    TXT_SALE.Focus();
     //    MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "PLEASE ENTER SALE PRICE!", MessageAlertImage.Alert());
     //    mdg.ShowDialog();
     //}
     //else if(Convert.ToDouble(TXT_SALE.Text) <= Convert.ToDouble(TXT_COST.Text))
     //{
     //    TXT_SALE.Focus();
     //    MSGBOX mdg = new MSGBOX(MessageAlertHeder.Alert(), "ENTERD SALE PRICE IS LESS THAN OR EQUAL COST PRICE!", MessageAlertImage.Alert());
     //    mdg.ShowDialog();
     //}
     else
     {
         ADD_TO_TABLE();
         CLEAR_BOX();
         CAL_TOTAL_COST();
         LBL_TOTAL_PAYABLE.Text = (Convert.ToDouble(LBL_TOT_GRN.Text) + Convert.ToDouble(LBL_PREVIOUS_DUES.Text)).ToString("F2");
         ITEM_CODE = String.Empty;
         ITEM_NAME = String.Empty;
         BARCODE   = String.Empty;
         TXT_ITEMNAME.Focus();
     }
 }