protected void btnPlaceOrder_Click(object sender, EventArgs e)
 {
     try
     {
         MSOPSClassesDataContext msops_dc = new MSOPSClassesDataContext();
         string message = null;
         msops_dc.USP_PlaceOrder(Convert.ToDateTime(txtODate.Text), Convert.ToDateTime(txtSDate.Text),
                                 ddlProductID.SelectedValue, ddlCustomerID.SelectedValue, Convert.ToInt32(txtQty.Text), ref message);
         lblMessage.Text = message;
     }
     catch (Exception ex)
     {
         lblMessage.Text = "Error : " + ex.Message;
     }
 }