รบกวนหน่อยครับ อยากสอบถามอาการERROR ที่บางทีเป็น บางทีก็ไม่เป็น ผมงงๆครับ c# winapp Access

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.OleDb;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace SchoolApp
{
    public partial class Form1 : Form
    {
        private OleDbConnection connection = new OleDbConnection();
        public Form1()
        {
            InitializeComponent();
            try {
                connection.ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|datadirectory|\Database.mdb";
                connection.Open();
                label1.Text = "Connection Success";
                connection.Close();

            }
            catch (Exception ex)
            {
                MessageBox.Show("Error" + ex);

            }
        }

        private void btnSave_Click(object sender, EventArgs e)
        {

            try {
                connection.Open();
                OleDbCommand command = new OleDbCommand();
                command.Connection = connection;
                command.CommandText = "insert into Student (Title,Fname,Lname,Bev) values('"+textBox1.Text.Trim()+ "','" + textBox2.Text.Trim() + "','" + textBox3.Text.Trim() + "','" + textBox4.Text.Trim() + "') ";

                command.ExecuteNonQuery();
                MessageBox.Show("DATA SAVED");
                connection.Close();
                Cleardata();
                Showdata();
            }
            catch(Exception ex)
            {
                MessageBox.Show("เกิดข้อผิดพลาดบางอย่าง"+ex);

            }
        }

        private void btnEdit_Click(object sender, EventArgs e)
        {
            try
            {
                
                    connection.Open();
                    OleDbCommand command = new OleDbCommand();
                    command.Connection = connection;
                    string query = "update Student set Title='" + textBox1.Text + "', Fname='" + textBox2.Text + "',Lname='" + textBox3.Text + "',Bev='" + textBox1.Text + "' where ID=" + textBox6.Text + "";
                    command.CommandText = query;

                    command.ExecuteNonQuery();
                    MessageBox.Show("DATA Edit Success");
                    connection.Close();
                    Cleardata();
                    Showdata();
                
            }
            catch 
            {
                MessageBox.Show("กรุณากลับไปเลือกและแก้ไขข้อมูลก่อนกดปุ่มแก้ไข");

            }
        }

        private void btnDelete_Click(object sender, EventArgs e)
        {
            try
            {
                connection.Open();
                OleDbCommand command = new OleDbCommand();
                command.Connection = connection;
                string query = "delete from Student where ID=" + textBox6.Text + "";
                command.CommandText = query;

                command.ExecuteNonQuery();
                MessageBox.Show("DATA Delete Success");
                connection.Close();
                Cleardata();
                Showdata();
            }
            catch 
            {
                MessageBox.Show("กรุณากลับไปเลือกข้อมูลก่อนกดปุ่มลบ" );

            }
        }

        private void btnLoad_Click(object sender, EventArgs e)
        {
            try
            {
                connection.Open();
                OleDbCommand command = new OleDbCommand();
                command.Connection = connection;
                string query = "select * from Student ";
                command.CommandText = query;

                OleDbDataAdapter da = new OleDbDataAdapter(command);
                DataTable dt = new DataTable();
                da.Fill(dt);
                dataGridView1.DataSource = dt;
                dataGridView1.Columns[0].HeaderText = "รหัส";
                dataGridView1.Columns[0].Width = 50;
                dataGridView1.Columns[1].HeaderText = "ชื่อ";
                dataGridView1.Columns[1].Width = 200;
                dataGridView1.Columns[2].HeaderText = "นามสกุล";
                dataGridView1.Columns[2].Width = 200;
                dataGridView1.Columns[3].HeaderText = "พฤติกรรม";
                dataGridView1.Columns[3].Width = 300;
                dataGridView1.Columns[4].HeaderText = "วันที่ ";
                dataGridView1.Columns[4].Width = 100;

                connection.Close();

            }
            catch (Exception ex)
            {
                MessageBox.Show("Eror" + ex);

            }
        }

        private void dataGridView1_CellMouseClick(object sender, DataGridViewCellMouseEventArgs e)
        {
            if (e.RowIndex>=0)
            {
                DataGridViewRow row = dataGridView1.Rows[e.RowIndex];
                textBox1.Text = row.Cells[1].Value.ToString();
                textBox2.Text = row.Cells[2].Value.ToString();
                textBox3.Text = row.Cells[3].Value.ToString();
                textBox4.Text = row.Cells[4].Value.ToString();
                textBox6.Text = row.Cells[0].Value.ToString();
            }
        }

        private void btnSearch_Click(object sender, EventArgs e)
        {
            try
            {
                connection.Open();
                OleDbCommand command = new OleDbCommand();
                command.Connection = connection;
                string query = "SELECT * FROM Student WHERE Title LIKE '%" + txtSearch.Text + "%'";
                command.CommandText = query;

                DataTable dt = new DataTable();
                OleDbDataAdapter da = new OleDbDataAdapter(command);

                da.Fill(dt);
                dataGridView1.DataSource = dt;
                dataGridView1.Columns[0].HeaderText = "รหัส";
                dataGridView1.Columns[0].Width = 50;
                dataGridView1.Columns[1].HeaderText = "ชื่อ";
                dataGridView1.Columns[1].Width = 200;
                dataGridView1.Columns[2].HeaderText = "นามสกุล";
                dataGridView1.Columns[2].Width = 200;
                dataGridView1.Columns[3].HeaderText = "พฤติกรรม";
                dataGridView1.Columns[3].Width = 300;
                dataGridView1.Columns[4].HeaderText = "วันที่ ";
                dataGridView1.Columns[4].Width = 100;

                connection.Close();

            }
            catch (Exception ex)
            {
                MessageBox.Show("Eror" + ex);

            }
        }

        private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
        {
            Bitmap bm = new Bitmap(this.dataGridView1.Width, this.dataGridView1.Height);
            dataGridView1.DrawToBitmap(bm, new Rectangle(0, 0, this.dataGridView1.Width, this.dataGridView1.Height));
            e.Graphics.DrawImage(bm, 0, 0);
        }

        private void btnPrint_Click(object sender, EventArgs e)
        {
            PrintDialog printDialog = new PrintDialog();
            printDialog.Document = printDocument1;
            printDialog.UseEXDialog = true;
            //Get the document
            if (DialogResult.OK == printDialog.ShowDialog())
            {
                printDocument1.DocumentName = "Test Page Print";
                printDocument1.Print();
            }
        }

        private void btnExit_Click(object sender, EventArgs e)
        {
            if (MessageBox.Show("ต้องการปิดโปรแกรม ?", "", MessageBoxButtons.YesNo) == DialogResult.Yes)
            {
                Application.Exit();
            }
        }

        private void Cleardata()
        {
            textBox1.Clear(); textBox2.Clear(); textBox3.Clear(); textBox4.Clear(); txtSearch.Clear(); textBox6.Clear();
        }


        private void Showdata()
        {
            try
            {
                connection.Open();
                OleDbCommand command = new OleDbCommand();
                command.Connection = connection;
                string query = "select * from Student ";
                command.CommandText = query;

                OleDbDataAdapter da = new OleDbDataAdapter(command);
                DataTable dt = new DataTable();
                da.Fill(dt);
                dataGridView1.DataSource = dt;
                dataGridView1.Columns[0].HeaderText = "รหัส";
                dataGridView1.Columns[0].Width = 50;
                dataGridView1.Columns[1].HeaderText = "ชื่อ";
                dataGridView1.Columns[1].Width = 200;
                dataGridView1.Columns[2].HeaderText = "นามสกุล";
                dataGridView1.Columns[2].Width = 200;
                dataGridView1.Columns[3].HeaderText = "พฤติกรรม";
                dataGridView1.Columns[3].Width = 300;
                dataGridView1.Columns[4].HeaderText = "วันที่ ";
                dataGridView1.Columns[4].Width = 100;

                connection.Close();

            }
            catch (Exception ex)
            {
                MessageBox.Show("Eror" + ex);

            }
        }

    }
}