Ch8 Actors - CheckActors gives dead letter errors

[shafiquejamal]

Hello, I'm having trouble with the CheckActors example in the book. When I try to run the following code:

class CheckActor extends Actor {

  import akka.actor.{Identify, ActorIdentity}
  val log = Logging(context.system, this)

  override def receive = {
    case path: String =>
      log.info(s"checking path $path")
      log.info(context.self.toString)
      log.info(context.parent.toString)
      context.actorSelection(path) ! Identify(path)
    case ActorIdentity(path, Some(ref)) =>
      log.info(s"found actor $ref at $path")
    case ActorIdentity(path, None) =>
      log.info(s"count not find an actor at path")

  }

}

// In main:
    val checker:ActorRef = ourSystem.actorOf(Props[CheckActor], "checker")
    checker ! "../*"

I get the following error (when running in the sbt console):

[INFO] [08/03/2016 14:55:29.998] [OurExampleSystem-akka.actor.default-dispatcher-2] [akka://OurExampleSystem/user/checker] checking path ../*
[INFO] [08/03/2016 14:55:29.999] [OurExampleSystem-akka.actor.default-dispatcher-2] [akka://OurExampleSystem/user/checker] Actor[akka://OurExampleSystem/user/checker#419406266]
[INFO] [08/03/2016 14:55:29.999] [OurExampleSystem-akka.actor.default-dispatcher-2] [akka://OurExampleSystem/user/checker] Actor[akka://OurExampleSystem/user]
[INFO] [08/03/2016 14:55:30.006] [OurExampleSystem-akka.actor.default-dispatcher-3] [akka://OurExampleSystem/user/checker] Message [akka.actor.ActorIdentity] from Actor[akka://OurExampleSystem/deadLetters] to Actor[akka://OurExampleSystem/user/checker#419406266] was not delivered. [1] dead letters encountered. This logging can be turned off or adjusted with configuration settings 'akka.log-dead-letters' and 'akka.log-dead-letters-during-shutdown'.
[success] Total time: 0 s, completed Aug 3, 2016 2:55:30 PM

I tried it with the code from the code files too, and get the same result (without the extra logging statements). Can you suggest what I might be doing wrong? Thanks.