ช่วยด้วยครับ Insert data .. using System.Data.SqlClient; using System.Data.OleDb;

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Data.SqlClient;
using System.Data.OleDb;
using System.IO;

namespace Welcome_form
{
    public partial class insertdatapolice : Form
    {
        public insertdatapolice()
        {
            InitializeComponent();
        }

        private void Showdata()
        {
            string conStr = "Data Source=(local); Integrated Security=True; Initial Catalog=Trafficpolice ";

            SqlConnection Conn = new SqlConnection(conStr);
            Conn.Open();

            String Sql = "SELECT * FROM Police";
            SqlCommand cmd = new SqlCommand(Sql, Conn);

            SqlDataAdapter adapter = new SqlDataAdapter(cmd);

            DataSet data = new DataSet();
            adapter.Fill(data, "Pol");

            dataGridView1.DataSource = data.Tables["Pol"];

            Conn.Close();
        }

        private void insertdatapolice_Load(object sender, EventArgs e)
        {
            this.WindowState = FormWindowState.Maximized;
            Showdata();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.Close();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            string conStr = "Data Source=(local); Integrated Security=True; Initial Catalog=Trafficpolice ";

            SqlConnection Conn = new SqlConnection(conStr);
            Conn.Open();

            String sql = "INSERT INTO Police VALUES(@Pol_login, @Pol_pass, @Pol_name, @Pol_lname, @Pol_sex, @Pol_phone, @Pol_station, @Pol_no)";

            SqlCommand cmd = new SqlCommand(sql, Conn);

            cmd.Parameters.AddWithValue("Pol_login", textBox1.Text);
            cmd.Parameters.AddWithValue("Pol_pass", textBox2.Text);
            cmd.Parameters.AddWithValue("Pol_name", textBox3.Text);
            cmd.Parameters.AddWithValue("Pol_lname", textBox4.Text);
            cmd.Parameters.AddWithValue("Pol_sex", textBox5.Text);
            cmd.Parameters.AddWithValue("Pol_phone", textBox6.Text);
            cmd.Parameters.AddWithValue("Pol_station", textBox7.Text);
            cmd.Parameters.AddWithValue("Pol_no", textBox8.Text);
            cmd.ExecuteNonQuery(); <------------มันติด error ตรงนี้ครับ
           
            Conn.Close();
            Showdata();
        }
    }
}