Redundancy in Ignition

I’m trying to create a script that get active when the server fail and the backup server starts. I have tryed with the tags isMaster and Role. But when I force a failover in my server and the backup server actives nothing happen. Both tags keep their old values.

Does anyone know which tags I can use to control when my application is runned by the backup server? Or if you have another trick, it is welcome too.