อยากทราบวิธีทำให้ combobox เลื่อน index ไปตาม textbox ครับกรุณาบอกหน่อย

Connect()
        SetCommand("select PD_Id,TP_Id,PD_Name,PD_Unit,PD_Sale from Product_Table")
        DSet = New DataSet
        Adpter.Fill(DSet, "Product_T")
        DTable = DSet.Tables("Product_T")

        Txt_RearchProduct.Text = ""


        Cbb_TypeP.DataSource = DTableTypeP
        Cbb_TypeP.DisplayMember = "TP_Name"
        Cbb_TypeP.ValueMember = "TP_Id"


โค้ด event Datagrid_Cick
 Dim IndexDatagrid As Integer = 0
        IndexDatagrid = Me.Dgv_Product.BindingContext(DTable).Position
        Dim ProId As String = 0
        ProId = Me.Dgv_Product.Rows(IndexDatagrid).Cells("PD_Id").Value

        Connect()
        SetCommand("select * from Product_Table where PD_Id=@Id")
        Cmd.Parameters.AddWithValue("Id", ProId)
        DSet = New DataSet
        Adpter.Fill(DSet, "Product_TGrid")

        DTableGrid = DSet.Tables("Product_TGrid")

        Txt_ProductId.DataBindings.Add("Text", DTableGrid, "PD_Id")
        Txt_TypePId.DataBindings.Add("Text", DTableGrid, "TP_Id")
        Txt_ProductName.DataBindings.Add("Text", DTableGrid, "PD_Name")
        Txt_ProductUnit.DataBindings.Add("Text", DTableGrid, "PD_Unit")
        Txt_ProductSale.DataBindings.Add("Text", DTableGrid, "PD_Sale")
        Lbl_ParthImage.DataBindings.Add("Text", DTableGrid, "PD_Img")