Download file from FTP Server using jQuery Ajax in ASP.Net

i try to download pdf from ftp server using same code that i used before in asp.net but it's not work. 

try
{
    FtpWebRequest request = (FtpWebRequest)WebRequest.Create(pathFile);
    request.Method = WebRequestMethods.Ftp.DownloadFile;
    request.Credentials = new NetworkCredential(username, password);
    request.UsePassive = true;
    request.UseBinary = true;
    request.EnableSsl = false;
    FtpWebResponse response = (FtpWebResponse)request.GetResponse();

    using (MemoryStream stream = new MemoryStream())
    {
        //Download the File.
        response.GetResponseStream().CopyTo(stream);
        HttpContext.Current.Response.AddHeader("content-disposition", "attachment;filename=" + fileName);
        HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.NoCache);
        HttpContext.Current.Response.BinaryWrite(stream.ToArray());
        HttpContext.Current.Response.End();
    }
}
catch (WebException ex)
{
    FtpWebResponse response = (FtpWebResponse)ex.Response;
    if (response.StatusCode == FtpStatusCode.ActionNotTakenFileUnavailable)
    {
        return false;
    }

    return false;
}