Ionic 4 Events work only on same page

Ionic Framework ionic-v3
1

hi there,

is use ionic 4 (all is up to date - today ;)) and i’ll use the Events (https://ionicframework.com/docs/api/util/Events/):
i trigger the event in the app.component.ts

changeCategory(category: Category) {
  console.log("event trigger from app");
  this.events.publish("category:changed", category);
}

and listen in the first page

  constructor(public events: Events) {
    this.subscribeEvents(events);
  }
  subscribeEvents(events: Events) {
    events.subscribe("category:changed", (category) => {
    // only executed from 'event trigger from news' not from 'event trigger from app'
      console.log("category from news page");
      console.log(category);
    });

    console.log("event trigger from news");
    this.events.publish("category:changed", "hi");
  }

what is my mistake?

greets
lars