Play 2.1.1 does not load Akka user manager

I use Play 2.1.1, and application.confadd the following custom dispatcher to:

# Dispatcher for round-robin actors
play {
    akka {
        actor {
            rr-dispatcher = {
                type = BalancingDispatcher
                executor = fork-join-executor
                fork-join-executor {
                    parallelism-min = 2
                    parallelism-factor = 2
                    parallelism-max = 24
                }
                # messages per actor before jumping
                throughput = 100
            }
        }
    }
}

I am trying to use it on an actor:

private val default = Akka.system.actorOf(Props[MessageRouterActor].withRouter(FromConfig()).withDispatcher("rr-dispatcher"), "msgRouter")

But I get this message that the dispatcher was not found:

[info] play - Starting application default Akka system.
[WARN] [04/20/2013 22:05:12.069] [application-akka.actor.default-dispatcher-5] [Dispatchers] Dispatcher [rr-dispatcher] not configured, using default-dispatcher

As I understand it, this is the right way to add it. Does anyone know what the problem is?