Specifying the LDAP Module in the Post-Authentication Section

You need to add 'ldap' in the post-authentication section of the install_path/etc/raddb/radiusd.conf file as shown below:

post-auth { 
         #  Get an address from the IP Pool.

ldap 
#       main_pool 
         # 
         #  If you want to have a log of authentication replies, 
         #  un-comment the following line, and the 'detail reply_log' 
         #  section, above. 
#       reply_log 
         # 
         #  After authenticating the user, do another SQL qeury. 
         # 
         #  See "Authentication Logging Queries" in sql.conf 
#       sql 
         # 
         #  Access-Reject packets are sent through the REJECT sub-section 
         #  of the post-auth section. 
         # 
       Post-Auth-Type REJECT { 
              ldap 
            }