c# 關於 upload code 無法上傳問題？

請教....
以下的 upload code ，當upload 之後會把原檔檔長變0，upload 上去的檔案也是0，不知是那裡的問題？
可否請高人指點...
tks.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;
using System.IO;
using System.Threading.Tasks;
using System.Net;
using System.Collections;


static class Constants
{
public const String FTP_IP = "ftp://192.168.1.1/";

}



namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{


ftp ftpClient = new ftp(@Constants.FTP_IP, "xxxxx", "xxxxxxxx");


/* Upload a File */
ftpClient.upload("sda/vba20150424175858.rar", @"c:\intel\vba20150424175858.rar");
}
}
}


class ftp
{
private string host = null;
private string user = null;
private string pass = null;
private FtpWebRequest ftpRequest = null;
private FtpWebResponse ftpResponse = null;
private Stream ftpStream = null;
private int bufferSize = 2048;

// Construct Object
public ftp(string hostIP, string userName, string password) { host = hostIP; user = userName; pass = password; }


/* Upload File */
public void upload(string remoteFile, string localFile)
{
try
{
/* Create an FTP Request */
ftpRequest = (FtpWebRequest)FtpWebRequest.Create(host + "/" + remoteFile);
/* Log in to the FTP Server with the User Name and Password Provided */
ftpRequest.Credentials = new NetworkCredential(user, pass);
/* When in doubt, use these options */
ftpRequest.UseBinary = true;
ftpRequest.UsePassive = true;
ftpRequest.KeepAlive = true;
/* Specify the Type of FTP Request */
ftpRequest.Method = WebRequestMethods.Ftp.UploadFile;
/* Establish Return Communication with the FTP Server */
ftpStream = ftpRequest.GetRequestStream();
/* Open a File Stream to Read the File for Upload */
FileStream localFileStream = new FileStream(localFile, FileMode.Create);
/* Buffer for the Downloaded Data */
byte[] byteBuffer = new byte[bufferSize];
int bytesSent = localFileStream.Read(byteBuffer, 0, bufferSize);
/* Upload the File by Sending the Buffered Data Until the Transfer is Complete */
try
{
while (bytesSent != 0)
{
ftpStream.Write(byteBuffer, 0, bytesSent);
bytesSent = localFileStream.Read(byteBuffer, 0, bufferSize);
}
}
catch (Exception ex) { Console.WriteLine(ex.ToString()); }
/* Resource Cleanup */
localFileStream.Close();
ftpStream.Close();
ftpRequest = null;
}
catch (Exception ex) { Console.WriteLine(ex.ToString()); }
return;
}