After you have created a secure http-listener and installed lbplugin, the magnus.conf and obj.conf files under the webserver_instance_dir/config directory are modifiedand the lbplugin contents are being removed.
The installer modifies the magnus.conf and obj.conf configuration files on the Application Server as part of the installation of the load balancer plug-in. If you log in to the Application Server admin console and try to manage the instance configuration for the instance on which the load balancer has been installed, the Application Server issues a warning message stating that it has detected a manual edit in the configuration. This warning is in fact referring to the changes made by the installer.
Verify that the changes made by the installer have not been overwritten.