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Depending on your Active Directory configuration, you also need to change the group names of authorized users in pentaho-solutions/system/pentaho.xml and pentaho-solutions/system/applicationContext-spring-security.xml.
References
[SEC-130: Support for Active Directory logins
How to login with a Windows Domain account|http://teamwork.jacobs-university.de:8080/confluence/display/ircit/How+to+login+with+a+Windows+Domain+account]
Javadoc for javax.naming.Context
Installing Pentaho BI Suite 3.6GA with Active Directory as LDAP