The problem in this case was the target system was setup for keyboard-interactive authentication.
The RSP probe no longer supports keyboar-interactive authentication.
Please see the documentation:
To test you can use the following commands:
plink.exe> -ssh username@xxx.xxx.xxx.xxx /b
in/uname -s -v -r -m
Using keyboard-interactive authentication.
Password:
Linux 3.0.101-0.7.17-default #1 SMP Tue Feb 4 13:24:49 UTC 2014 (90aac76) x86_64
NOTE: The below changes can be made to sshd configuration file to allow the rsp probe to work. PLEASE CHECK WITH SYSTEM ADMIN FIRST!!!!
(NOTE - Support is not responsible for affects brought by SSH config changes. Consult System Admin before change)
PermitRootLogin yes (Default value - Comment out)
PasswordAuthentication yes (Default value - no)
PermitEmptyPasswords no (Default value - Comment out)