Can't connect; connection refused

I've trying out ExpanDrive 1.8.3 for Windows, and I'm getting this message when I try to connect "We were able to contact the server, but it refused your connection. Check to see if the server's SSH component is running or if a firewall is blocking access." I've tried turning off my antivirus and firewall, and that's not the problem. I'm sure I've got my credentials right, because they work in FileZilla. Any ideas, ExpanDrive?