DataGrid视图不使用Access数据库显示新添加的记录

Question

我是C＃的新手，我想尽快这样做，因为我上周以来遇到过这个问题。我尝试了一些方法，但还没有得到正确的输出。这是我的代码：

private void btnDelete_Click(object sender, EventArgs e)
    {
        try
        {
            String itemcode = tbItemCode.Text.ToString();
            String shade = tbShade.Text.ToString();
            String rollnumber = tbRollNumber.Text.ToString();

            System.Data.OleDb.OleDbConnection conn = new System.Data.OleDb.OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\Eranga\Documents\Visual Studio 2010\Projects\RollAllocationModel\RollAllocationModel\Roll.mdb;Persist Security Info=True;Jet OLEDB:Database Password=admin");
            String deletequery = "DELETE FROM TabRoll WHERE (ItemCode = '" + itemcode + "') AND (Shade = '" + shade + "') AND (RollNumber = '" + rollnumber + "')";
            //String deletequery = "SELECT * FROM TabRoll";
            //code by query builder ----> DELETE FROM TabRoll WHERE (ItemCode = '" + itemcode + "') AND (Shade = '" + shade + "') AND (RollNumber = '" + length + "');
            conn.Open();

            OleDbDataAdapter da = new OleDbDataAdapter(deletequery, conn);
            OleDbCommandBuilder cb = new OleDbCommandBuilder(da);
            DataTable dt = new DataTable();
            da.Fill(dt);

            BindingSource bSource = new BindingSource();
            bSource.DataSource = dt;


            dataGridView1.EndEdit();
            bSource.EndEdit();
            da.Update(dt);
            dataGridView1.DataSource = bSource;

            conn.Close();
            MessageBox.Show("Data deleted");
        }
        catch (Exception exceptionObj)
        {
            MessageBox.Show(exceptionObj.Message.ToString());
        }
    }

为什么DataGrid不会使用新记录进行更新。