命名空间名称'html'在命名空间iTextSharp v5.4.0中不存在

Question

我有一个问题，我想转换为PDF使用版本v5.4.0使用iTextSharp 1.命名空间'iTextSharp.text'中不存在类型或命名空间名称'html'（您是否缺少装配参考？）
2.当前上下文中不存在名称“PdfWriter” 3.当前上下文中不存在名称“HTMLWorker”

{
    string fileName = "pdfDocument" + DateTime.Now.Ticks + ".pdf";
    Response.Clear();
    GeneratePDF("", fileName, true, "");
    Response.ContentType = "application/pdf";
    Response.AddHeader("content-disposition", "attachment; filename=" + fileName);
    Response.Flush();
    Response.End();
}
protected void GeneratePDFAndDownload(object sender, EventArgs e)
{

    string fileName = "pdfDocument" + DateTime.Now.Ticks + ".pdf";
    Response.Clear();
    GeneratePDF("", fileName, true, "");
    Response.ContentType = "application/pdf";
    Response.AddHeader("content-disposition", "attachment; filename=" + fileName);
    Response.Flush();
    Response.End();
}

private void GeneratePDF(string path, string fileName, bool download, string text)
{
    var document = new Document();
    try
    {
        if (download)
        {
            PdfWriter.GetInstance(document, Response.OutputStream);
        }
        else
        {
            PdfWriter.GetInstance(document, new FileStream(path + fileName, FileMode.Create));
        }


        StringBuilder strB = new StringBuilder();
        document.Open();

        if (text.Length.Equals(0)) 
        {
            BindMyGrid();
            using (StringWriter sWriter = new StringWriter(strB))
            {
                using (HtmlTextWriter htWriter = new HtmlTextWriter(sWriter))
                {
                    istorijaKupovinaGreedView.RenderControl(htWriter);
                }
            }
        }
        else 
        {
            strB.Append(text);
        }


        using (TextReader sReader = new StringReader(strB.ToString()))
        {
            List<IElement> list = HTMLWorker.ParseToList(sReader, new StyleSheet());
            foreach (IElement elm in list)
            {
                document.Add(elm);
            }
        }
    }
    catch (Exception ee)
    {
        lblMessage.Text = ee.ToString();
    }
    finally
    {
        document.Close();
    }
}

private void BindMyGrid()
{
    throw new NotImplementedException();
}

}