Siteminder 6, Apache 2.0.4.2, Enterprise Portal 6- SP15, AIX

Enterprise portal server front ended with apache reverse proxy server which hosts Siteminder web agent 6.0. Enterprise portal server and backend SAP application servers all configured to use sap logon tickets. Enterprise portal server "ticket" login module stack configured to accept "HeaderVariableLoginModule" as optional criteria. We verified that Siteminder web agent is indeed sending "HTTP_LDAP_UID" (LDAP userid header variable). However, Enterprise portal is not accepting header variable as authentication and still challenged for basic UID password authentication even through reverse proxy. I will gladly provide screenshots as needed. Has anyone made this setup work, we need your assistance. Thanks in advance.