Data not saved in datagrid

namespace National_items
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }
        
        private bool savetag = false;

        private void AdditemBtn_Click(object sender, EventArgs e)
        {
            try
            {
                DataRow row;
                DataTable table = itemsListDataSet.Devlist;
                row = table.NewRow();
                row[0] = textBox1.Text;
                row[1] = textBox2.Text;
                table.Rows.Add(row);
            }
            catch(Exception)
            {
                MessageBox.Show("This Item was inserted", "Confirm", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void Form2_Load(object sender, EventArgs e)
        {
            // TODO: This line of code loads data into the 'itemsListDataSet.Devlist' table. You can move, or remove it, as needed.
            this.devlistTableAdapter.Fill(this.itemsListDataSet.Devlist);
            savetag = true;
        }
        
        private void SavItemBtn_Click(object sender, EventArgs e)
        {
            devlistTableAdapter.Connection.Open();
            devlistTableAdapter.Fill(itemsListDataSet.Devlist);
            itemsListDataSet.GetChanges();
            devlistBindingSource.EndEdit();
            devlistTableAdapter.Connection.Close();
            savetag = true;
        }

        private void DelItemBtn_Click(object sender, EventArgs e)
        {
            dataGridView1.Rows.Remove(dataGridView1.CurrentRow);
        }
       
        private void Form2_FormClosing(object sender, FormClosingEventArgs e)
        {
            if (savetag == false)
            { 
                DialogResult dr = MessageBox.Show("Do you want to save changes", "Confirme", MessageBoxButtons.YesNoCancel, MessageBoxIcon.Question,MessageBoxDefaultButton.Button1);
                if (dr == DialogResult.Cancel)
                    e.Cancel = true;
                else if (dr == DialogResult.Yes)
                    SavItemBtn_Click(sender, e);
            }
        }

        private void dataGridView1_CellValueChanged(object sender, DataGridViewCellEventArgs e)
        {
            savetag = false;
        }
    }
}