Question on pam_radius_auth module getting INCORRECT password

Hi, I am new to this. Please let me know if there is a better list to post this question. My system is running RHEL and using a separate FreeRadius server to authenticate ssh user logins. All regular user credentials are stored on the radius server. I have been trying to track down a wired problem. When a user is logging via ssh, the pam_radius_auth module would try to retrieve the password and send it to the radius server. But the password returned by the rad_converse() function is INCORRECT. I have done some searching and found suggestions that there might be something wrong with "other" module that is doing the password checking. My real question is how I can find out which module is the culprit. David