I am currently trying to convert GridView that is generated into a pdf file. Unfortunately, I am constantly getting this error:

"Unable to cast object of type 'ITextSharp.text.html.simpleparser.CellWrapper' to type 'iTextSharp.text.Paragraph'.

I will include the code for reference and I really hope any of u guys can point ou the cause of the error.

.cs:

protected void GenerateReport(object sender, EventArgs e)

{

            Response.ContentType = "application/pdf";
            Response.AddHeader("content-disposition", "attachment;filename=GridViewExport.pdf");
            Response.Cache.SetCacheability(HttpCacheability.NoCache);
            StringWriter sw = new StringWriter();
            HtmlTextWriter hw = new HtmlTextWriter(sw);
            HtmlForm frm = new HtmlForm();
            GridView1.AllowPaging = false;
            GridView1.Parent.Controls.Add(frm);
            frm.Attributes["runat"] = "server";
            frm.Controls.Add(GridView1);
            frm.RenderControl(hw);
            GridView1.DataBind();
            GridView1.RenderControl(hw);
            StringReader sr = new StringReader(sw.ToString());
            Document pdfDoc = new Document(PageSize.A4, 10f, 10f, 10f, 0f);
            HTMLWorker htmlparser = new HTMLWorker(pdfDoc);
            PdfWriter.GetInstance(pdfDoc, Response.OutputStream);
            pdfDoc.Open();
            pdfDoc.Close();
            Response.Write(pdfDoc);
            Response.End();

}

.aspx:

 Report Format:<asp:DropDownList ID="ddlReportFormat" runat="server">
    <asp:ListItem Text="Please Select A Format" Value="default"></asp:ListItem> 
    <asp:ListItem Text="Excel" Value="1"></asp:ListItem>
    <asp:ListItem Text="Word" Value="2"></asp:ListItem>
    <asp:ListItem Text="PDF" Value="3"></asp:ListItem>
    </asp:DropDownList>
    <asp:Button ID="repSel" runat="server" Text="Generate Report" OnClick="GenerateReport"/>

Thanks in advance!