I use gftp for all transfer work, regardless of protocol. It should be included with the distro, and it's in the build repositories.
You can get a better idea of what's going wrong by opening a console (terminal) and manually entering something like,
Code:
sftp 111.111.111.111
... where "111.111.111.111" is the IP address or the name of the server. (Try it both ways.) Note that by default, it will log in as the current user. If you need to specify a particular username, use something like
Code:
sftp -oUser MyUserName 111.111.111.111
See "man sftp" at that same terminal prompt for more info. The error messages returned at a prompt should be very specific; if you continue to have trouble, post the results back here.