ListBox datasource is not updated on first click

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C#

MS-Access

ListBox

i create a winform program that load the data from ms access database to my listbox. when i click my item which i want to update on database and datasource on my listbox and click the update button, the item just wont update for the first time clicked but the second does(on the same item), so everytime i need to modify my data i need to choose my item and click the update button two times. that's is crazy lol..

private void Fill()
        {
            string strSQL = "SELECT * FROM Item ORDER BY ITEM";
            OleDbDataAdapter myCmd = new OleDbDataAdapter(strSQL, GetConnection());
            DataSet dtSet = new DataSet();
            myCmd.Fill(dtSet, "Item");
            DataTable dTable = dtSet.Tables[0];
            foreach (DataRow dtRow in dTable.Rows)
            {
                _productlist.Add(new PRODUCTLIST() { ID = dtRow["ID"].ToString(), ITEM = dtRow["ITEM"].ToString(), ITEM_DESC = dtRow["ITEM_DESC"].ToString() });
            }
            listBox1.DisplayMember = "ITEM";
            listBox1.DataSource = _productlist;
            listBox1.ValueMember = "ID";
            GetConnection().Close();
        }

    private void Form1_Load(object sender, EventArgs e)
        {
            // make ID textbox un editable
            textBoxID.Enabled = false;

            // fill the listbox
            Fill();

            textBoxID.DataBindings.Add("Text", _productlist, "ID", false, DataSourceUpdateMode.Never);
            textBoxITEM.DataBindings.Add("Text", _productlist, "ITEM", false, DataSourceUpdateMode.Never);
            textBoxITEMDESC.DataBindings.Add("Text", _productlist, "ITEM_DESC", false, DataSourceUpdateMode.Never);
        }

private void buttonUpdate_Click(object sender, EventArgs e)
        {
            //update the database
            OleDbDataAdapter cmd = new OleDbDataAdapter();
            cmd.UpdateCommand = new OleDbCommand("UPDATE Item SET ITEM = @ITEM, ITEM_DESC = @ITEM_DESC WHERE ID = @ID",GetConnection());
            cmd.UpdateCommand.Parameters.AddWithValue("@ITEM", textBoxITEM.Text);
            cmd.UpdateCommand.Parameters.AddWithValue("@ITEM_DESC", textBoxITEMDESC.Text);
            cmd.UpdateCommand.Parameters.AddWithValue("@ID", Convert.ToInt32(textBoxID.Text));
            cmd.UpdateCommand.ExecuteNonQuery();

            // update the datasource
            _productlist.Clear();
            listBox1.DataSource = null;
            listBox1.Items.Clear();
            Fill();
            listBox1.Update();
        }

basic thing that happen:

1. load data to listbox with databind to textbox
2. click item on my listbox and modify data from textbox
3. click the update button to update database and datasource
4. datasource not update for the first time but database does update
5. repeat no.2
6. repeat no.3
7. datasource updated

what i want:

1. load data to listbox with databind to textbox
2. click item on my listbox and modify data from textbox
3. click the update button to update database and datasource
4. datasource and database updated

how do i fix this bug on my application?? please let me know if i need to be more clear..