NO BATCHES FOR TRANSMISSION

We've upgraded our XI server and now when connecting to an FTP site to pick up a file we are receiving the following error...

Could not process due to error: com.sap.aii.adapter.file.ftp.FTPEx: 550 *** ERROR *** NO BATCHES FOR TRANSMISSION

Has anyone seen this error?

Also the file does exist and is able to be picked up by our server that wasn't upgraded.

Thanks