C#将XLS文件上传到FTP

我使用以下代码将*.xls文件上传到FTP。它可以很好地上传，但FTP中*.xls文件的内容都扰乱了

FtpWebRequest request = (FtpWebRequest)WebRequest.Create(@"ftp://www.xxxxxx.com" + fileName);
request.Method = WebRequestMethods.Ftp.UploadFile;

request.Credentials = new NetworkCredential("username", "password");
StreamReader sourceStream = new StreamReader(filePath);
byte[] fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());
sourceStream.Close();
request.ContentLength = fileContents.Length;
Stream requestStream = request.GetRequestStream();
requestStream.Write(fileContents, 0, fileContents.Length);
requestStream.Close();
FtpWebResponse response = (FtpWebResponse)request.GetResponse();
Console.WriteLine("Upload File Complete, status {0}", response.StatusDescription);
response.Close();

有人知道如何解决这个问题吗？？？？？？？

StreamReader sourceStream = new StreamReader(filePath);
byte[] fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());
sourceStream.Close();

byte[] fileContents = File.ReadAllBytes(filePath);