When you create a reference in the load balancer to a stand-alone server or cluster, the server or cluster is added to the list of target servers and clusters the load balancer controls. The referenced server or cluster still needs to be enabled (using enable-http-lb-server) before requests to it are load balanced. If you created the load balancer configuration with a target, that target is already added as a reference.
Create a reference using create-http-lb-ref. You must supply the load balancer configuration name and the target server instance or cluster.
For more information, see the documentation for create-http-lb-ref and delete-http-lb-ref.