Joli
Perhaps the first thing is to confirm that SSH is enabled. So can you post the output of show ip ssh
Assuming that the previous item confirms that SSH is enabled and running then the next question may be to ask how you are invoking SSH. What platform are you on when you attempt SSH, and how is SSH started?
I have had the experience from some platforms (especially Cisco routers or switches) that if I am in a session for which they have authenticated me, that if I use the SSH command to initiate a SSH session to some other device that it starts SSH and passes my current user ID to the new device. Is it possible that the user ID on your current device is not a valid user ID on the device where you are trying to DDH?
HTH
Rick
HTH
Rick