Тренировка PredictionIO на heroku дает требование не выполнено: viewEvents в PreparedData не может быть пустым

Question

Я следую руководству в https://www.jamesward.com/2016/06/14/machine-learning-on-heroku-with-predictionio/ и при запуске:heroku run -a <YOUR HEROKU APP NAME> train Я получаю ниже ошибки:

Exception in thread "main" java.lang.IllegalArgumentException: requirement failed: viewEvents in PreparedData cannot be empty. Please check if DataSource generates TrainingData and Preprator generates PreparedData correctly.
    at scala.Predef$.require(Predef.scala:233)
    at ALSAlgorithm.train(ALSAlgorithm.scala:44)
    at ALSAlgorithm.train(ALSAlgorithm.scala:38)
    at io.prediction.controller.P2LAlgorithm.trainBase(P2LAlgorithm.scala:46)
    at io.prediction.controller.Engine$$anonfun$18.apply(Engine.scala:689)
    at io.prediction.controller.Engine$$anonfun$18.apply(Engine.scala:689)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:244)
    at scala.collection.immutable.List.foreach(List.scala:318)
    at scala.collection.TraversableLike$class.map(TraversableLike.scala:244)
    at scala.collection.AbstractTraversable.map(Traversable.scala:105)
    at io.prediction.controller.Engine$.train(Engine.scala:689)
    at io.prediction.controller.Engine.train(Engine.scala:174)
    at io.prediction.workflow.CoreWorkflow$.runTrain(CoreWorkflow.scala:65)
    at TrainApp$delayedInit$body.apply(TrainApp.scala:72)
    at scala.Function0$class.apply$mcV$sp(Function0.scala:40)
    at scala.runtime.AbstractFunction0.apply$mcV$sp(AbstractFunction0.scala:12)
    at scala.App$$anonfun$main$1.apply(App.scala:71)
    at scala.App$$anonfun$main$1.apply(App.scala:71)
    at scala.collection.immutable.List.foreach(List.scala:318)
    at scala.collection.generic.TraversableForwarder$class.foreach(TraversableForwarder.scala:32)
    at scala.App$class.main(App.scala:71)
    at TrainApp$.main(TrainApp.scala:7)
    at TrainApp.main(TrainApp.scala)

Я вижу, что данные существуют в БД postgre.

Кто-нибудь имел это или знает, как "Пожалуйста, проверьте, генерирует ли DataSource TrainingData, а Preprator генерирует PreparedData правильно".?

Спасибо!