Unable to download .zip file from FTP

Uri url = new Uri("ftp://ftp.demo.com/file1.txt");
if (url.Scheme == Uri.UriSchemeFtp)
{
    FtpWebRequest objRequest = (FtpWebRequest)FtpWebRequest.Create(url);
    //Set credentials if required else comment this Credential code
    NetworkCredential objCredential = new NetworkCredential("FTPUserName", "FTPPassword");
    objRequest.Credentials = objCredential;
    objRequest.Method = WebRequestMethods.Ftp.DownloadFile;
    FtpWebResponse objResponse = (FtpWebResponse)objRequest.GetResponse();
    StreamReader objReader = new StreamReader(objResponse.GetResponseStream());
    byte[] buffer = new byte[16 * 1024];
    int len = 0;
    FileStream objFS = new FileStream(Server.MapPath("file1.txt"), FileMode.Create, FileAccess.Write, FileShare.Read);
    while ((len = objReader.BaseStream.Read(buffer, 0, buffer.Length)) != 0)
    {
        objFS.Write(buffer, 0, len);
    }
    objFS.Close();
    objResponse.Close();
}

public static void DownloadFTPFiles(string ftpAddress, string UserName, string Password)
{
    FtpWebRequest reqFTP = (FtpWebRequest)FtpWebRequest.Create(ftpAddress);

    try
    {
        reqFTP.UsePassive = true;
        reqFTP.UseBinary = true;
        reqFTP.KeepAlive = false;
        reqFTP.Credentials = new NetworkCredential(UserName, Password);
        reqFTP.Method = WebRequestMethods.Ftp.ListDirectory;
        FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();

        Stream responseStream = response.GetResponseStream();
        List<string> files = new List<string>();
        StreamReader reader = new StreamReader(responseStream);
        while (!reader.EndOfStream)
            files.Add(reader.ReadLine());
        reader.Close();
        responseStream.Dispose();
        List<periodicalfile> lstFiles = new List<periodicalfile>();
        //Loop through the resulting file names.
        string ftpPath = string.Empty;
        foreach (var fileName in files)
        {
            var parentDirectory = "";                   
            if (fileName.Contains(".zip"))
            {
                ftpPath = ftpAddress + fileName;
                wc.Credentials = new NetworkCredential(UserName, Password);
                wc.DownloadFile(file.FTPFileName, DestinationFolder + fileName);//DOWLOAD FROM FTP
            }
            else
            {
                //If the filename has no extension, then it is just a folder. 
                //Run this method again as a recursion of the original:
                parentDirectory += fileName + "/";
                try
                {
                    DownloadFTPFiles(ftpAddress + "/" + parentDirectory, UserName, Password);
                }
                catch (Exception ex)
                {
                    ErrorLog.WriteLog("ftpFileProcessing", "DownloadFTPFiles(Else)", ex.Message, ex.StackTrace, "");
                }
            }
        }
    }
    catch (Exception excpt)
    {
        reqFTP.Abort();
        ErrorLog.WriteLog("ftpFileProcessing", "DownloadFTPFiles", excpt.Message, excpt.StackTrace, "");
    }
}