Problem with button in crystal report toolbar

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ASP.NET

Hello sir,

I am working with crystal reports. I created a button on crystal report toolbar using the following code:

reportDocument = (ReportDocument)Session["reportDocument"];
       CrystalReportViewer1.ReportSource = reportDocument;
        System.Web.UI.Control oControl = CrystalReportViewer1.Controls[2];
        //Button oButton = new Button();
        //oButton.ID = "newButton";
        //oButton.Text = "My New Button";
        //oControl.Controls.Add(oButton);
        ImageButton BtnExport = new ImageButton();
        BtnExport.ID = "BtnExport";
        BtnExport.ImageUrl = "~/images/xls.png";
        // BtnExport.ToolTip = "Zoom";
        BtnExport.Click += ImgBtnXls_Click;
        BtnExport.EnableViewState = true;
        oControl.Controls.Add(BtnExport);
        UpdatePanel UpdatePanel1 = new UpdatePanel();

        System.Web.UI.PostBackTrigger trigger = new System.Web.UI.PostBackTrigger();

        trigger.ControlID = BtnExport.UniqueID.ToString();
        UpdatePanel1.Triggers.Add(trigger);

My problem is whenever I click the button to export the report, it shows an error like below:

Microsoft JScript runtime error: Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed. Common causes for this error are when the response is modified by calls to Response.Write(), response filters, HttpModules, or server trace is enabled.
Details: Error parsing near '�ࡱ�'.

If anyone knows the reason, please help me.