C# การใช้งาน BindingSource กับ combobox แบบบ้าน บ้าน

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // TODO: This line of code loads data into the 'postCodeDataSet.Sett_Post_PostCode' table. You can move, or remove it, as needed.
            this.sett_Post_PostCodeTableAdapter.Fill(this.postCodeDataSet.Sett_Post_PostCode);
            // TODO: This line of code loads data into the 'postCodeDataSet.Sett_Post_Province' table. You can move, or remove it, as needed.
            this.sett_Post_ProvinceTableAdapter.Fill(this.postCodeDataSet.Sett_Post_Province);

        }

        private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            this.Text = comboBox1.SelectedValue.ToString();
            bindingSource2.Filter = "Pnv = " + comboBox1.SelectedValue;
        }
    }
}

            // comboBox1
            // 
            this.comboBox1.DataSource = Datatable; // เพิ่มจาก Datatable 
            this.comboBox1.DisplayMember = "Province";
            this.comboBox1.FormattingEnabled = true;
            this.comboBox1.Location = new System.Drawing.Point(40, 12);
            this.comboBox1.Name = "comboBox1";
            this.comboBox1.Size = new System.Drawing.Size(259, 21);
            this.comboBox1.TabIndex = 0;
            this.comboBox1.ValueMember = "pvnID";