Looks like your client is knocking at the door but getting refused.

What kind of access to the remote system do you have?

If you have root access, you might be able to run 'sshd -vV' and then retry your program. You will see all the messages from the server end. I've found those error messages tend to say more than the client when troubleshooting.

Note: You will have to kill the currently running sshd to start a new sshd.

-Kurt