Java Security

Hi

I have an implementation of apache 1.3.20 with tomcat 3.2.3. I an doing
auth. with a ldap server wihich works prefectly with apache
mod_auth_ldap (module). When i am trying to read the environment
variables with a cgi , REMOTE_USER returns me the authentificated user
but when i am doing a getremoteuser() in my servlet with tomcat , it
returns NULL Why ?

I came accross this page when looking for material and

http://www.peacetech.com/java/files/apache/tomcat/

did the following

1) Downloaded - jndi_auth_beta1.jar, Extracted jndi_auth.jar file which contained
class files and plcaed them inside my tomcat/lib directory

2) Then i have updated the server.xml file of my Tomcat, that i wanted to use LDAPRealm

<RequestInterceptor className="com.peacetech.webtools.tomcat.LdapRealm"
debug="1"
directoryUrl = "ldap://csee.usf.edu:389"
searchBaseContext = "o=usf.edu"
searchFilter = "uid={0}"
searchScopeAsString = "sub"
securityAttributes = "securityEquals"
attributesReadByOwner = "true"
connectionMaxPoolSize = "10"
ldapVersion = "3" />

Then i had shutdown and restarted the server after some initial hickups, then i have tried to open some sample JSP and sevlets in the examples directory of my server. But i was not asked for any UserId/Password. Was wondering if i have done anything wrong ??

Thanks
Arun