Добавление записей в таблицу Access при помощи C#

В моем проекте имеется кнопка "Добавить запись в Access". После того, как я записал все необходимые для добавления данные, я нажимаю на кнопку. После этого возникает данная ошибка, если в таблице Access нет каких либо данных (пустая).

P.S. Код прилагается.

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 Authorization
{
    public partial class fGroup : Form
    {
        OleDbConnection requireConnect = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\BD_Primer1.accdb");
        BindingSource BindnSource;
        DataTable DataTab;
        bool forBtns;
        public fGroup()
        {
            InitializeComponent();
            cbSpecialty.SelectedIndex = 0;
            LoadDataFromAccess();
            forBtns = false;
        }
        void LoadDataFromAccess()
        {
            OleDbDataAdapter adapter = new OleDbDataAdapter("Select * from Groups", requireConnect);
            DataTab = new DataTable();
            adapter.Fill(DataTab);
            BindnSource = new BindingSource();
            BindnSource.DataSource = DataTab;
            bindingNavigator1.BindingSource = BindnSource;
            nCourse.DataBindings.Clear();
            nCourse.DataBindings.Add(new Binding("Text", BindnSource, "course"));
            tbNumberOfGroup.DataBindings.Clear();
            tbNumberOfGroup.DataBindings.Add(new Binding("Text", BindnSource, "numberOfGroup"));
            cbSpecialty.DataBindings.Clear();
            cbSpecialty.DataBindings.Add(new Binding("Text", BindnSource, "specialty"));
            dataAboutGroups.DataSource = BindnSource;
            dataAboutGroups.Columns[0].Visible = false;
            dataAboutGroups.Columns[1].HeaderText = "Курс";
            dataAboutGroups.Columns[2].HeaderText = "Специальность";
            dataAboutGroups.Columns[3].HeaderText = "Номер группы";
            dataAboutGroups.Columns[1].AutoSizeMode = DataGridViewAutoSizeColumnMode.Fill;
            dataAboutGroups.Columns[2].AutoSizeMode = DataGridViewAutoSizeColumnMode.Fill;
            dataAboutGroups.Columns[3].AutoSizeMode = DataGridViewAutoSizeColumnMode.Fill;
            dataAboutGroups.RowsDefaultCellStyle.WrapMode = DataGridViewTriState.True;
        }
        private void ClearText()
        {
            nCourse.Text="1";
            tbNumberOfGroup.Text = "";
            cbSpecialty.SelectedIndex = 0;
        }
        private void addBtn_Click(object sender, EventArgs e)
        {
            ClearText();
            forBtns = true;
            saveBtn.Enabled = false;
        }
        private void tbNumberOfGroup_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (!Char.IsDigit(e.KeyChar) && e.KeyChar != 8) e.Handled = true;
        }
        private void delBtn_Click(object sender, EventArgs e)
        {
            if (forBtns)
            {
                //отмена
                ClearText();
                forBtns = false;
                saveBtn.Enabled = true;
                LoadDataFromAccess();
            }
            else if (BindnSource.Count > 0)
            {
                //удаление
                int rowPosition = BindnSource.Position;
                int delId = Convert.ToInt32(((DataRowView)this.BindnSource.Current).Row["ID_group"]);
                try
                {
                    DialogResult result = MessageBox.Show(
                    "Вы действительно хотите удалить данную запись",
                    "Удаление",
                    MessageBoxButtons.YesNo,
                    MessageBoxIcon.Question,
                    MessageBoxDefaultButton.Button1,
                    MessageBoxOptions.DefaultDesktopOnly);
                    if (result == DialogResult.No)
                    {
                        LoadDataFromAccess();
                        return;
                    }
                    if (result == DialogResult.Yes)
                    {
                        requireConnect.Open();
                        OleDbCommand Delete = new OleDbCommand("Delete From Groups where ID_group = @ID", requireConnect);
                        Delete.Parameters.AddWithValue("@ID", delId);
                        Delete.ExecuteNonQuery();
                    }
                }
                finally
                {
                    requireConnect.Close();
                    LoadDataFromAccess();
                }
            }
        }
        private void saveBtn_Click(object sender, EventArgs e)
        {
            if (forBtns)
            {
                try
                {
                    requireConnect.Close();
                    requireConnect.Open();
                    OleDbCommand IdCount = new OleDbCommand("Select Max(ID_group) from Groups", requireConnect);
                    int max = 0;
                    if (IdCount.ExecuteScalar() != null)  max = Convert.ToInt32(IdCount.ExecuteScalar()); 
                    //добавление новых данных
                    OleDbCommand Insert = new OleDbCommand("INSERT INTO [Groups] VALUES(@ID_group, @course, @specialty, @numberOfGroup)", requireConnect);
                    Insert.Parameters.AddWithValue("@ID_group", max + 1);
                    Insert.Parameters.AddWithValue("@course", nCourse.Text);
                    Insert.Parameters.AddWithValue("@specialty", cbSpecialty.Text);
                    Insert.Parameters.AddWithValue("@numberOfGroup", tbNumberOfGroup.Text);
                    Insert.ExecuteNonQuery();
                    MessageBox.Show(
                    "Запись успешно добавлена",
                    "Сохранение",
                    MessageBoxButtons.OK,
                    MessageBoxIcon.Information,
                    MessageBoxDefaultButton.Button1,
                    MessageBoxOptions.DefaultDesktopOnly);
                    forBtns = false;
                    saveBtn.Enabled = true;
                }
                finally
                {
                    requireConnect.Close();
                    LoadDataFromAccess();
                }
            }
            else if (BindnSource.Count > 0)
            {
                //сохранение отредактированных данных
                int position = BindnSource.Position;
                int updateId = Convert.ToInt32(((DataRowView)this.BindnSource.Current).Row["ID_group"]);
                try
                {
                    requireConnect.Close();
                    requireConnect.Open();
                    OleDbCommand Update = new OleDbCommand("UPDATE Groups SET Course=@course, Specialty=@specialty, numberOfGroup=@numberOfGroup WHERE ID_group=@update_ID", requireConnect);
                    Update.Parameters.AddWithValue("@course", nCourse.Text);
                    Update.Parameters.AddWithValue("@specialty", cbSpecialty.Text);
                    Update.Parameters.AddWithValue("@numberOfGroup", tbNumberOfGroup.Text);
                    Update.Parameters.AddWithValue("@update_ID", updateId);
                    Update.ExecuteNonQuery();
                    MessageBox.Show("Запись обновлена");
                }
                finally
                {
                    requireConnect.Close();
                    LoadDataFromAccess();
                    BindnSource.Position = position;
                }
            }
        }
        private void tbNumberOfGroup_TextChanged(object sender, EventArgs e)
        {
            if (this.Text == "") saveBtn.Enabled = false;
            else saveBtn.Enabled = true;
        }
    }
}