Problem with ftp web request

[libish]

hi all,

i'm trying to develop a file uploader, it uses ftp, language is c# the application is c#windows app
the main part of code that i use is as below

try
            {
FtpWebRequest request; 
            request = getFTPRequestObject(strNewFile);
                request.ContentLength = fileInfo.Length;

requestStream = request.GetRequestStream();

                FileStream fileStream = fileInfo.OpenRead();
                contentLen = fileStream.Read(buffer, 0, buffLength);

                while (contentLen != 0)
                {
                    requestStream.Write(buffer, 0, contentLen);
                    contentLen = fileStream.Read(buffer, 0, buffLength);

                }
                fileStream.Close();


requestStream.Close();



                //FtpWebResponse response = (FtpWebResponse)request.GetResponse();
                //strMessage = response.StatusDescription;
                //responseCode = Convert.ToInt32(response.StatusCode);
                //response.Close();
            }

        private FtpWebRequest getFTPRequestObject(string strFileName)
        {
            FtpWebRequest requestOb = (FtpWebRequest)WebRequest.Create(Path.Combine(ConstantClass.strFTPsiteUrl, strFileName));
            string strUserName =ConstantClass.USERNAME;
            string strPassword=ConstantClass.PASSWORD;
            requestOb.Credentials = new NetworkCredential(strUserName,strPassword);//("vmftp", "veomed123#");
            requestOb.Method = WebRequestMethods.Ftp.UploadFile;
            requestOb.UseBinary = true;
            requestOb.Timeout = Timeout.Infinite;
            requestOb.ReadWriteTimeout = Timeout.Infinite;
            requestOb.Proxy = null;

            requestOb.KeepAlive = true;//false
            requestOb.EnableSsl = false;
            requestOb.UsePassive = false;
            return requestOb;
        }

the listed part is where i have problem with
i have many files to upload
i put them in a queue and am uploading one at a time...
it all works perfect.. but when i have a big file for upload say a 80 mb .ppt file,
it succeed in writing it to ftp site but aftr writing ie after exiting from the code below

      while (contentLen != 0)
                {
                    requestStream.Write(buffer, 0, contentLen);
                    contentLen = fileStream.Read(buffer, 0, buffLength);

                }

it gets stuck or waits unconditionally at

requestStream.Close();

can any one help me out,