สอบถามการใส่ Code LoadReport ใน Page_Init กับคำสั่ง PostBack และ Session ของ Report (vb.net)

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
        <asp:Button ID="Button1" runat="server" style="margin-bottom: 0px" Text="Button" />
        <CR:CrystalReportViewer ID="CrystalReportViewer1" runat="server" AutoDataBind="true" />

Imports System.Data.SqlClient
Imports CrystalDecisions.CrystalReports.Engine
Imports CrystalDecisions.Shared
Public Class WebForm1
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

    End Sub

    Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim objConn As New SqlConnection
        Dim objCmd As New SqlCommand
        Dim dtAdapter As New SqlDataAdapter

        Dim ds As New DataSet
        Dim dt As DataTable
        Dim strConnString, strSQL As String

        strConnString = "Server= ... ;UID=sa;PASSWORD=....;database=....;Max Pool Size=400;Connect Timeout=600;"
        strSQL = "SELECT * FROM vwReport WHERE Date BETWEEN '" & Me.TextBox1.Text & "' AND '" & Me.TextBox2.Text & "' "

        objConn.ConnectionString = strConnString
        With objCmd
            .Connection = objConn
            .CommandText = strSQL
            .CommandType = CommandType.Text
        End With
        dtAdapter.SelectCommand = objCmd

        dtAdapter.Fill(ds, "myDataTable")
        dt = ds.Tables(0)

        dtAdapter = Nothing
        objConn.Close()
        objConn = Nothing

        Dim rpt As New ReportDocument()
        rpt.Load(Server.MapPath("CrystalReport1.rpt"))
        rpt.SetDataSource(dt)
        Me.CrystalReportViewer1.ReportSource = rpt
        Me.CrystalReportViewer1.RefreshReport()
    End Sub
End Class