Custom ASP.NET YetGridView DataSource ไม่จดจำค่าเมื่อ PostBack

Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Text
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls

Public Class YetGridView
    Inherits GridView

    <Bindable(False), Category("Appearance"), DefaultValue("Text"), Localizable(True), Description("Set GridView Pattern")>
    Public Property _PatternCode As String
        Get
            If ViewState("_PatternCode") Is Nothing Then
                Return String.Empty
            Else
                Return CType(ViewState("_PatternCode"), String)
            End If
        End Get
        Set(ByVal Value As String)
            ViewState("_PatternCode") = Value
        End Set
    End Property

    ''' <summary>
    ''' Keep GridView DataSource After Postback
    ''' </summary>
    ''' <value>Example Me._Model = New List(Of Products)</value>
    ''' <remarks></remarks>
    Public Property _DataModel As List(Of Object)
        Get
            If ViewState("_DataModel") Is Nothing Then
                Return Nothing
            Else
                Return CType(ViewState("_DataModel"), List(Of Object))
            End If
        End Get
        Set(ByVal Value As List(Of Object))
            ViewState("_DataModel") = Value
        End Set
    End Property

    Protected Overrides Sub OnPageIndexChanging(e As System.Web.UI.WebControls.GridViewPageEventArgs)
        If ViewState("_DataModel") IsNot Nothing Then
            Me.PageIndex = e.NewPageIndex
            Me.DataSource = DirectCast(ViewState("_DataModel"), List(Of Object))
            Me.DataBind()
            MyBase.OnPageIndexChanging(e)
        End If
    End Sub

    Protected Overrides Sub OnRowDataBound(e As System.Web.UI.WebControls.GridViewRowEventArgs)
        For Each c As TableCell In e.Row.Cells
            c.ToolTip = c.Text
        Next
        MyBase.OnRowDataBound(e)
    End Sub

    ''' <summary>
    ''' Get current Active Column Index
    ''' </summary>
    ''' <param name="SortExp"></param>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Private Function GetColumnIndex(ByVal SortExp As String) As Integer
        For s As Short = 0 To Me.Columns.Count - 1
            Try
                If Me.Columns(s).SortExpression.Equals(SortExp, StringComparison.CurrentCultureIgnoreCase) Then
                    Return s
                End If
            Catch ex As Exception
                'Ignore Error
            End Try
        Next
        Return -1
    End Function
    ''' <summary>
    ''' 
    ''' </summary>
    ''' <param name="c">HL, IL, FL</param>
    ''' <returns>Enum</returns>
    ''' <remarks>HL = Header Alignment, IL = Item Alignment, FL = Footer Alignment</remarks>
    Private Function GetColumnAlignment(ByVal c As String) As [Enum]
        Try
            Select Case c.Trim().Substring(1, 1).ToUpper()
                Case "C"
                    Return HorizontalAlign.Center
                Case "R"
                    Return HorizontalAlign.Right
                Case Else
                    Return HorizontalAlign.Left
            End Select
        Catch ex As Exception
            Return HorizontalAlign.Left
        End Try
    End Function

End Class

<script src="/ScriptResource.axd?d=Yet_yr0iO2ixFsZ8bxj3PgxhBptll9Hofyxc-XfsqAZ2RxFDep2hJ1szm4Fdl7C30ZVALIyUVKX1Ak1pVdTBKMmENyoyD4NzjqQWygdO5snrr9oqGWxpnrMwfnq68K-MQxCl2Pat-n7YtrqHbW3nkRBcYg2&amp;t=7c776dc1_Yet" type="text/javascript"></script>

Imports System
Imports System.Reflection
Imports System.Runtime.InteropServices

Imports System.Web.UI

' General Information about an assembly is controlled through the following 
' set of attributes. Change these attribute values to modify the information
' associated with an assembly.

' Review the values of the assembly attributes

<Assembly: AssemblyTitle("YetGridView")> 
<Assembly: AssemblyDescription("")> 
<Assembly: AssemblyCompany("")> 
<Assembly: AssemblyProduct("YetGridView")> 
<Assembly: AssemblyCopyright("Copyright ©  1960-2013")> 
<Assembly: AssemblyTrademark("")> 

<Assembly: ComVisible(False)> 

'The following GUID is for the ID of the typelib if this project is exposed to COM
<Assembly: Guid("d8075dab-b3a9-4083-ac8c-0c187d3f2b6f")> 

' Version information for an assembly consists of the following four values:
'
'      Major Version
'      Minor Version 
'      Build Number
'      Revision
'
' You can specify all the values or you can default the Build and Revision Numbers 
' by using the '*' as shown below:
' <Assembly: AssemblyVersion("1.0.*")> 

<Assembly: AssemblyVersion("1.0.*")> 
<Assembly: AssemblyFileVersion("1.0.0.0")> 
<Assembly: WebResource("YetGridView.YetGridView.js", "text/javascript", PerformSubstitution:=True)> 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using System.Dynamic;
using System.Data;

namespace WebApplicationCS
{
    public partial class DynamicObject_A : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            dynamic p = new ExpandoObject();
            p.Title = "Using Dynamic";
            p.Data = new Action(() =>
            {
                DataTable dt = new DataTable();
                dt.Columns.Add("ProductCode", typeof(string));
                dt.Columns.Add("ProductName", typeof(string));

                dt.Rows.Add(new object[] { "001", "Car" });
                dt.Rows.Add(new object[] { "002", "food" });
                dt.Rows.Add(new object[] { "003", "bed" });

                GridView1.DataSource = dt;
                GridView1.DataBind();
            });
            Response.Write("<center><b>" + p.Title + "</center></b>");
            p.Data();
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

using System.Dynamic;
using System.Data;

namespace WebApplicationCS
{
    public partial class DynamicObject_A : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            dynamic p = new ExpandoObject();
            p.Title = "Using System.Dynamic";
            p.Data = new Action(() =>
            {
                DataTable dt = new DataTable();
                dt.Columns.Add("ProductCode", typeof(string));
                dt.Columns.Add("ProductName", typeof(string));

                dt.Rows.Add(new object[] { "001", "Car" });
                dt.Rows.Add(new object[] { "002", "food" });
                dt.Rows.Add(new object[] { "003", "bed" });

                GridView1.DataSource = dt;
                GridView1.DataBind();
            });
            Response.Write("<center><b>" + p.Title + "</center></b>");
            p.Data();
        }
    }
}

    Protected Sub Button1_Click(sender As Object, e As System.EventArgs) Handles Button1.Click
        Dim p As Object = New ExpandoObject()

        p.Title = "Using System.Dynamic"
        p.Data = Sub()
                     Dim dt As New DataTable
                     dt.Columns.Add("ProductCode", GetType(String))
                     dt.Columns.Add("ProductName", GetType(String))

                     dt.Rows.Add(New Object() {"001", "Car"})
                     dt.Rows.Add(New Object() {"002", "food"})
                     dt.Rows.Add(New Object() {"003", "bed"})

                     GridView1.DataSource = dt
                     GridView1.DataBind()
                 End Sub

        Response.Write("<center><b>" + p.Title + "</b></center>")
        p.Data.Invoke()
    End Sub