ขอความช่วยเหลือค่ะ เพิ่งเริ่มเขียนอะค่ะ แล้วเกิด error แบบนี้(มีรูปค่ะ)ไม่ทราบว่าควรแก้ยังไงคะ

Dim Data As String = GridView3.DataKeys(currentRowIndex).Value

 Dim Data As String = GridView3.DataKeys(currentRowIndex).Value

    Protected Sub Row_Select3(ByVal sender As Object, ByVal e As GridViewCommandEventArgs) Handles GridView3.RowCommand
        Dim conse3 As New SqlConnection(ConfigurationManager.ConnectionStrings("LN").ConnectionString)
        Dim cmdse3 As New SqlCommand("Select ttimfc010601.t_mser,ttimfc010601.t_mitm FROM ttimfc010601 WHERE ttimfc010601.t_mitm and ttimfc010601.t_mser and ttimfc010601.t_pdno=@se ", conse3)
        cmdse3.CommandType = CommandType.Text
        Dim currentCommand3 As String = e.CommandName
        Dim currentRowIndex As Integer = Int32.Parse(e.CommandArgument)
        Dim Data As String = GridView3.DataKeys(currentRowIndex).Value
        cmdse3.Parameters.Add("@se", SqlDbType.Char).Value = Data
        Dim dase As New SqlDataAdapter(cmdse3)
        Dim dsse As New DataSet
        Dim drse As DataRow
        dase.Fill(dsse)
        For Each drse In dsse.Tables(0).Rows
            Me.TextBox24.Text = ""
            Me.TextBox24.Text &= (drse("t_mser"))
        Next
        conse3.Close()
        Me.GridView3.Visible = False
        Me.TextBox26.Visible = False

    End Sub

    Sub serial2()
        Dim conea As New SqlConnection(ConfigurationManager.ConnectionStrings("LN").ConnectionString)
        Dim cmdea As New SqlCommand("Select ttimfc010601.t_mser,ttimfc010601.t_mitm FROM ttimfc010601 WHERE ttimfc010601.t_mitm like '%" & Me.TextBox26.Text & "%'", conea)
        cmdea.CommandType = CommandType.Text
        Dim da As New SqlDataAdapter(cmdea)
        Dim ds As New DataSet
        da.Fill(ds, "ser1")
        Me.GridView3.DataSource = ds.Tables("ser1")
        Me.GridView3.DataBind()
        conea.Close()

    End Sub