[Serusers] how to load radius-related modules in ser 0.8.14?

Dear all, I'm new to SER. I wish to use softphone X-lite on SER and radius in db_mode. I have installed SER 0.8.14 (by tarball) and Mysql 3.23.54 in Redhat 9. Also, I have added some subscribers into DB "ser". After setting /usr/local/etc/ser/ser.cfg as the document "iptel.org SIP Express Router v0.11.0 -- Admin's Guide"(http://www.iptel.org/ser/doc/seruser/seruser.html#DEFAULTSCRIPT) guided, I could load the modules "auth" and "auth_db" and successfully log any subscriber that Mysql contains in X-lite. And now, I want to load radius-related modules: "acc", "auth_radius", "group_radius", "uri_radius" in SER. But when I put only one line: "loadmodule "/usr/local/lib/ser/modules/auth_radius.so"" in ser.cfg and then run ser, there is an error reply: "ERROR: bad config file (1 errors)". How come? How to load those modules properly? Many thanks. Shuai http://www.godentek.biz