Check that you have the correct sshd entries in /etc/pam.conf on the AIX agent.
If pf_authenticateonclient = true, the authenticate_pam_toclient() is called using the "sshd" pam service.
The pam configuration on the AIX systems will need to be set to allow sshd.
It should have entries similar to the following:
sshd auth required pam_aix
sshd account required pam_aix
sshd password required pam_aix
sshd session required pam_aix