Connect Database?? คับ ... ทำบน Pocket PC คับ ทำเสร็จมัน Error ตรง cn.open(); ฐานข้อมูล SqlCE คับ

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.SqlServerCe;
using System.Data.SqlClient;


namespace Traffic_Police_For_PPC
{
    public partial class ppclogin : Form
    {
        public ppclogin()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            bool blnfound = false;

            string con = "Data Source=\\My Documents\\Databases\\Trafficpolice.sdf;Persist Security Info=False;";

            SqlConnection cn = new SqlConnection(con);
            cn.Open();


            SqlCommand cmd = new SqlCommand("select * from police", cn);

            SqlDataReader dr = cmd.ExecuteReader();

            while (dr.Read())
            {



                if (dr["Pol_login"].ToString() == textBox1.Text)
                {


                    if (dr["Pol_pass"].ToString() == textBox2.Text)
                    {

                        blnfound =

                        true;
                        //MessageBox.Show("ยินดีต้อนรับเข้าสู่ Traffic Police Application On PPC", "Log in Successful", MessageBoxButtons.OK);
                        menuform f = new menuform();
                        f.Show();
                        this.Hide();
                    }

                }

            }


            if (blnfound == false)

                //MessageBox.Show("Username หรือ Password ไม่ถูกต้อง กรุณาใส่ข้อมูลใหม่  ", "Log in Failed");

            dr.Close();

            cn.Close();

        }

        private void Form1_Load(object sender, EventArgs e)
        {

        }

        private void button2_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}