Object reference not set to an instance of an object.

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C#

i am having this problem when i try to save my file... it initially says that there is no object but in the locals i can see the data stored.i tried this code from a tutorial but it seems to fail when i try......... ;(


.. why cant i refer it to the right place. moreover i can save the file but in the end the file ends up empty when i try to open it.








code is this...

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO; 
using System.Runtime.Serialization.Formatters.Binary;
using System.Runtime.Serialization;

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

        private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
        {

        }

        private void saveToolStripMenuItem_Click(object sender, EventArgs e)
        {
            SaveFileDialog saveFileDialog1 = new SaveFileDialog();
            saveFileDialog1.ShowDialog();
            saveFileDialog1.RestoreDirectory = true;
            //read aur compare data
            if (saveFileDialog1.ShowDialog() == DialogResult.OK)
            {
                BinaryFormatter formatter = new BinaryFormatter();
                FileStream output = new FileStream(saveFileDialog1.FileName,
                    FileMode.OpenOrCreate, FileAccess.Write);

                int n = GRID.RowCount;
                data[] person = new data[n - 1];//rows minus one for an empty data line
                for (int i=0; i < n - 1; i++)
                {
                   
                        person[i] = new data();
                        person[i].name = GRID[0, i].Value.ToString();
                        person[i].contact = GRID[1, i].Value.ToString();
                        person[i].phnumber = GRID[2, i].Value.ToString();
                        person[i].address = GRID[3, i].Value.ToString();
                  
                }
                Formatter.Equals(output, person);

                output.Close();
            }
        }

     
    }
    [Serializable] //for saving file
    public class data
    {
        public string name;
        public string contact;
        public string phnumber;
        public string address;
    }
}