how to show the report in asp.net page using Devexpress report?

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C#

ASP.NET

DevExpress

Hi all,
Am new in DevExpress Report wizard in asp.net c#
am trying to show the report on my web page using xtrareports.
i have done the report design within the xtrareports.
but i cannot show the design on my web page.

i tried below code to show the report on my web page but am getting the below error,
please have a look at the code below,

please drop me a solution for this.

my error is :
Object reference not set to an instance of an object.

my code is :

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

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

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        // Create a report. 
        XtraReport1 report = new XtraReport1();
        // Show the report's preview. 
        ReportPrintTool tool = new ReportPrintTool(report);
        tool.ShowPreview();
   
        
    }
}

thanks in advance...