Tomcat needs to be started with JMX enabled (warning: insecure setup!):
JAVA_OPTS=-Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=9004 -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false
See Also:Monitoring and Management Using JMX author: Cédrik LIME