Kryo not serializing configured classes

[fedenusy]

For some reason, kryo serialization is not working. Even though (I think) I set up kryo properly, the following warning keeps popping up:

WARN  17:42:27.913UTC akka.serialization.Serialization(akka://vw) - Using the default Java serializer for class [life.vw.client.ConciergeTracker$StatusUpdate] which is not recommended because of performance implications. Use another serializer or disable this warning using the setting 'akka.actor.warn-about-java-serializer-usage'

My build.sbt has this dependency:

"com.github.romix.akka" %% "akka-kryo-serialization" % "0.4.1"

I'm using akka 2.4.8 and scala 2.11.8. Here are the relevant portions of my application.conf:

akka {
  ...

  extensions = [
    "akka.cluster.pubsub.DistributedPubSub",
    "com.romix.akka.serialization.kryo.KryoSerializationExtension$"
  ]

  actor {
    ...

    kryo {
      type = "graph"
      idstrategy = "automatic"
      buffer-size = 4096
      max-buffer-size = -1
      use-manifests = false
      post-serialization-transformations = "lz4"
      kryo-trace = false
      implicit-registration-logging = true

      mappings {
        "life.vw.client.ConciergeTracker$StatusUpdate" = 30,
        "life.vw.client.Connection$Write" = 31
      }
    }
  }

  serializers {
    kryo = "com.romix.akka.serialization.kryo.KryoSerializer"
  }

  serialization-bindings {
    "life.vw.client.ConciergeTracker$StatusUpdate" = kryo
    "life.vw.client.Connection$Write" = kryo
  }

  ...
}

Any idea why the warning keeps popping up? Could it have something to do with the DistributedPubSub extension?

[fedenusy]

I was supposed to nest serializers and serialization-bindings under akka.actor T_T