唉，为什么不对？连接Oracle - .NET技术 / ASP.NET

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.OracleClient;




public partial class Query : System.Web.UI.Page
{
  protected void Page_Load(object sender, EventArgs e)
  {
  Label3.Text = "";
  }

  protected void Button1_Click(object sender, EventArgs e)
  {
  if (TextBox1.Text =="")
  {
  //MessageBox.Show("請輸入P001！", "操作提示");
  Label3.Text = "請輸入P001！";
  }
  string constring = "Server=192.168.2.81;Data Source=BRISA;Persist Security Info=True;User ID=roebrisa;Password=roemanager;Unicode=True";
  OracleConnection conn = new OracleConnection(constring);
  conn.Open();

  string sqlstring = "select MR_NO from r_wip_panel where SHIPPING_PALLET_NO='" + TextBox1.Text.ToString().Trim() + "' ";
  OracleCommand cmd = new OracleCommand(sqlstring, conn);

  try
  {
  string result = cmd.ExecuteOracleScalar().ToString().Trim();
  TextBox2.Text = result;