c# FTP ftpwebrequest URI invalid

i think the file name may be incorrect but i cannot tell why this throwing this exception.
any ideas?

fileName = "c:/soapmessages/OUT/" + var_yr + var_mth + var_day + "_XXXXXXX.csv";

error:
System.Net.WebException: The requested URI is invalid for this FTP command.
   at System.Net.FtpWebRequest.GetRequestStream()
   at XXXXXXXX.Program.Main(String[] args) in J:\mastersource\XXXXXX\ConsoleApplication2\Program.cs:line 179

string ftpfullpath = Path.GetFileName(ftpFile);
              FtpWebRequest ftp = (FtpWebRequest)FtpWebRequest.Create(new Uri(ftpFile));
              ftp.Credentials = new NetworkCredential(ftpUserID, ftpPassword);

              ftp.KeepAlive = true;
              ftp.UseBinary = true;
              ftp.Method = WebRequestMethods.Ftp.UploadFile;

              FileStream fs = File.OpenRead(fileName);
              byte[] buffer = new byte[fs.Length];
              fs.Read(buffer, 0, buffer.Length);
              fs.Close();

             [b] Stream ftpstream = ftp.GetRequestStream();      <--- line 179[/b]
              ftpstream.Write(buffer, 0, buffer.Length);
              ftpstream.Close();