The following are some of the areas in which problems often occur:
The i-Planet server must be able to resolve whether the userid is a local or NIS userid. For example, if the passwd entry in the /etc/nsswitch.conf file specifies something like nis [NOTFOUND=return] files then the system will not find a local userid.
If you click on the module link in the login page and keep receiving the same page back, check the file reversepolicy.policy on the i-Planet gateway.
Make sure that you restarted the reverse proxy server on the i-Planet gateway.
If you do not see the module that you have added as a choice on the login page, start the Administration Console again.
Make sure the authentication module that you have added (in this example, com.sun.login.radius.Radius) is listed under the Authentication Modules. You may have forgotten to click the Enter button at the bottom of the page to save your changes, or you did not stop and restart the web server for the changes to take effect.