Ann, If you have ruled out the authentication side of things then can you confirm the URL that I gave earlier does not work with summary. I have mentioned it a couple of times now but you have not confirmed whether it works or not.
to restate, using a command line ftp client with correct authentication the 1st URL below did NOT work. However the second URL DID work ok.
Relative URL -Failure ftp://goose.xssl.net/var/log/httpd/error_log URL with recursion up directory tree - Success ftp://goose.xssl.net/../../var/log/httpd/error_log
change goose to your server name and try. If this and authentication is checked out, then you can only go back to the summary developers and query how their application works as myself and others have suggested.
Hope this helps and please let us know how you get on.