Help! The remote server returned an error: (550) File unavailable

Hi all, 
This code is supposed to FTP a file from my server to a remote website when I click the upload button.  I get an error message.
   [WebException: The remote server returned an error: (550) File unavailable (e.g., file not found, no access).]
   System.Net.FtpWebRequest.SyncRequestCallback(Object obj) +321
   System.Net.FtpWebRequest.RequestCallback(Object obj) +19
   System.Net.CommandStream.Abort(Exception e) +163
   System.Net.FtpWebRequest.FinishRequestStage(RequestStage stage) +453
   System.Net.FtpWebRequest.GetRequestStream() +880
   upload.uploadFileUsingFTP(String CompleteFTPPath, String CompleteLocalPath, String UName, String PWD) +199
   upload.cmdUpload_Click(Object sender, EventArgs e) +36
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +105
   System.Web.UI.WebControls.Button.RaisePost ...