c#代码出错

using System;
using System.Collections.Generic;
using
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace WindowsFormsApplication9
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            SqlConnection conn = new SqlConnection();
            conn.ConnectionString = "server=USER-20160806SI\\SQLEXPRESS;uid=sa;pwd=sa database=luke";
            conn.Open();
            DataTable dt = new DataTable("resouce");
            dt.Clear();
            string sql = "insert into text1 values('" + textBox1.Text + "','" + textBox2.Text + "','" + textBox3.Text + "')";
            SqlCommand command = new SqlCommand(sql, conn);
            SqlDataAdapter ad = new SqlDataAdapter();
            ad.SelectCommand = command;
            ad.Fill(dt);
            dt.Clear();
            SqlDataAdapter adp=new SqlDataAdapter("select * from text1",conn);
            adp.Fill(dt);
            dataGridView1.DataSource=dt.DefaultView;
        }
    }
}

  提示sa登陆失败，但是我的其它代码这么连接都没问题啊，不知错在哪里