Before you can create server instances for a cluster, you must first create a node agent or node agent placeholder. See To Create a Node Agent Placeholder
In the tree component, expand the Clusters node.
Select the node for the cluster.
Click the Instances tab to bring up the Clustered Server Instances page.
Click New to bring up the Create Clustered Server Instance page.
In the Name field, type a name for the server instance.
Choose a node agent from the Node Agents drop-down list.
Click OK.
create-instance