download files from ftpserver to local system

See more:

C#

.NET

I want to know weather the files is fully downloaded in ftpserver from local system.
I written a code that will download the files which are dropped in certain folder path in ftp server.my problem is when a file of size above 2 MB is dropped in ftpserver folder before it gets fully downloaded in my code it starts downloading the file and finally it download half of the content I want to find that the file in ftpserver is fully downloaded and then only i want to start download to local system. here is my code please any one reply me i searched for more than four days. Thanks in advance.

while (fileQueue.Count > 0)
            {
                string fileName = fileQueue.Dequeue();
                int getindex = fileName.LastIndexOf("/");
                string getsubfile = fileName.Substring(getindex, fileName.Length - getindex);                
                
                string filePath = localPath;
                string srnew = fileName.Replace("ftp://" + ftpServerIP + ftpPath, " ");
                FtpWebRequest reqFTP;
                FileStream outputStream;

                try
                {
                    //reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp://" + ftpServerIP + ftpFolderName + fileName));
                    reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(fileName));
                    reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
                    reqFTP.UseBinary = true;
                    reqFTP.Credentials = new NetworkCredential(ftpUserID, ftpPassword);
                    FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
                    Stream ftpStream = response.GetResponseStream();
                    long cl = response.ContentLength;
                    // this.Invoke(new MethodInvoker(delegate { dataGridView1.Rows[count].Cells[3].Value = cl; }));
                    int bufferSize = 2048;
                    int readCount;
                    byte[] buffer = new byte[bufferSize];
                    //Random rand = new Random();
                    // byte nextByte;  
                     int folderindex = srnew.LastIndexOf("/");
                     string folderfile = srnew.Substring(0, folderindex);                              
                    if (folderfile != string.Empty)
                    {
                        if (Directory.Exists(localPath +folderfile))
                        {

                        }
                        else
                        {
                            Directory.CreateDirectory(localPath + folderfile);
                            //writetextDownAfter(localPath + sr.Trim() + "/" + strname.Trim());
                        }
                    }
                    readCount = ftpStream.Read(buffer, 0, bufferSize);
                    int i = 1;
                    while (File.Exists(filePath + srnew.Trim()))
                    {
                        string[] over = srnew.Split('.');
                        over[0] = over[0] + i.ToString();
                        srnew = over[0] + "." + over[1];
                        i++;
                    }

                    outputStream = new FileStream(filePath + srnew, FileMode.Create);
                    //Stopwatch sw = new Stopwatch();
                    //sw.Start();
                    this.Invoke(new MethodInvoker(delegate { dataGridView1.Rows.Add("Server1", getsubfile.ToString(), "Downloading"); }));
                    int count = dataGridView1.Rows.Count - 2;
                    this.Invoke(new MethodInvoker(delegate { dataGridView1.FirstDisplayedScrollingRowIndex = dataGridView1.Rows.Count - 1; }));
                    while (readCount > 0)
                    {
                        outputStream.Write(buffer, 0, readCount);
                        if (ftpStream.CanSeek)
                        {
                            long lll = ftpStream.Position;
                        }
                        readCount = ftpStream.Read(buffer, 0, bufferSize);
                    }
                    ftpStream.Close();
                    //outputStream.Close();
                    response.Close();
                    //this.Invoke(new MethodInvoker(delegate { dataGridView1.Rows[count].Cells[0].Value="Server1";}));
                    //this.Invoke(new MethodInvoker(delegate { dataGridView1.Rows[0].Cells[1].Value = getsubfile; }));
                    this.Invoke(new MethodInvoker(delegate { dataGridView1.Rows[count].Cells[2].Value = "Downloaded"; }));
                    this.Invoke(new MethodInvoker(delegate { dataGridView1.FirstDisplayedScrollingRowIndex = dataGridView1.Rows.Count - 1; }));
                    //this.Invoke(new MethodInvoker(delegate { dataGridView1.Rows.Add("Server1", getsubfile.ToString(), "Downloaded"); }));
                }
                catch (WebException ex)
                {
                    string errMsg = (ex.Message);
                    fileQueue.Enqueue(fileName);
                    //MessageBox.Show("webexe"+ex.Message.ToString());

                }
                catch (Exception ex)
                {
                    string errMsg = (ex.Message);
                    MessageBox.Show("exe" + ex.Message.ToString());

                }