VB.Net ติดปัญหาเกี่ยวกับการสร้าง Dynamic Gridview ครับ

Public Class WebForm10
    Inherits System.Web.UI.Page
    Dim dtHead As DataTable
    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

    End Sub

    Protected Sub btn_search_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btn_search.Click
        If GridView1.Rows.Count > 0 Then
            GridView1.Columns.Clear()
        End If

        AddTemplate()

        addDatasource()
    End Sub

    Sub AddTemplate()
        Dim objTransaction As New transaction
        Dim resultDtHead As New DataTable

        resultDtHead = objTransaction.selectAllHeadGridview(dropCompany.SelectedValue, dropItem.SelectedValue)

        Session("bound_head") = resultDtHead

        Dim j As Integer


        For j = 0 To resultDtHead.Rows.Count - 1
            Dim dCol As New TemplateField()
            dCol.HeaderText = resultDtHead.Rows(j)("cost_name")
            dCol.ItemTemplate = New GridviewTemplate1(ListItemType.Item, resultDtHead.Rows(j)("cost_name"), j)
            GridView1.Columns.Add(dCol)
        Next
    End Sub
    Sub addDatasource()
        Dim objTransaction As New transaction
        Dim resultDtHead As New DataTable
        Dim resulthead As New DataTable
        Dim str_head_cost As String = ""


        resulthead = objTransaction.selectHeadGridview(dropCompany.SelectedValue, dropItem.SelectedValue)

        Dim k As Integer

        For k = 0 To resulthead.Rows.Count - 1
            If str_head_cost.Trim = "" Then
                str_head_cost = resulthead.Rows(0)("cost_name")
            Else
                str_head_cost = str_head_cost & "," & resulthead.Rows(k)("cost_name")
            End If
        Next

        Dim resultDt As New DataTable
        resultDt = objTransaction.selectDetailForWaitApp(dropCompany.SelectedValue, dropItem.SelectedValue, str_head_cost)
        Session("bound_data") = resultDtHead
        GridView1.DataSource = resultDt
        GridView1.DataBind()
    End Sub

    Protected Sub GridView1_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles GridView1.RowDataBound

        dtHead = Session("bound_head")


        Dim i As Integer

        For i = 0 To dtHead.Rows.Count - 1
            If i <> 0 Then


                Dim lblHead As Label = CType(e.Row.FindControl(dtHead.Rows(i)("cost_name")), Label)
                If Not IsNothing(lblHead) Then
                    If e.Row.DataItem(dtHead.Rows(i)("cost_name")).ToString.Trim.Length > 0 Then
                        lblHead.Text = e.Row.DataItem(dtHead.Rows(i)("cost_name"))
                    Else
                        lblHead.Text = "-"
                    End If

                End If
            End If
        Next


    End Sub



    Protected Sub Button2_Click1(ByVal sender As Object, ByVal e As EventArgs) Handles Button2.Click
     

    End Sub

 
End Class

Public Class GridviewTemplate1
    Implements ITemplate

    Dim templateType As ListItemType
    Dim str_id As String
    Dim str_no As Integer
    Sub New(ByVal type As ListItemType, ByVal str_cost As String, ByVal no As Integer)
        templateType = type
        str_id = str_cost
        str_no = no
    End Sub


    Public Sub InstantiateIn(ByVal container As System.Web.UI.Control) _
        Implements System.Web.UI.ITemplate.InstantiateIn


        If str_no = 0 Then
            Dim cb As New CheckBox
            'cb.AutoPostBack = True
            cb.ID = "chkId"
            container.Controls.Add(cb)
        Else
            Select Case (templateType)
                Case ListItemType.Header
                    Dim txt As New TextBox
                    txt.Text = "Header"

                    container.Controls.Add(txt)
                Case ListItemType.Item
                    Dim lbl As New Label
                    lbl.ID = str_id

                    container.Controls.Add(lbl)

                Case ListItemType.Footer
                    Dim txt As New TextBox
                    container.Controls.Add(txt)
            End Select
        End If

       } 
    End Sub

End Class