In a cluster environment, when an active node fails over to the passive node, the path that is failing over to maybe a different path. This would be the path to executable where the launcher resides. If this path does not match or misspelled from the service, you will not be able to failover to the passive node.
Path to executable is incorrect.
Open services and right-click on 'QAM Launcher port#' --> properties and verify the path to executable if it matches the actual path from the monitored host.