error when trying to run a notification with ng-snotify

Using this library

Run the command:

npm install ng-snotify

Add the css to angular.json :

"node_modules/ng-snotify/styles/material.css",

My app.module.ts : - import it like so:

import { SnotifyModule, SnotifyService, ToastDefaults } from 'ng-snotify';

• declare it in the import like so:

SnotifyModule,

• also add it to providers :

providers: [ { provide: 'SnotifyToastConfig', useValue: ToastDefaults}, SnotifyService ],

In my ts :

• I import it like this:

import { Snotify, SnotifyService } from 'ng-snotify';

• In the constructor I declare it like this:

private service: SnotifyService

• I try to call a notification with a function like this:

showSuccess() {
  console.log('showSuccess');
  this.service.success('Example body content', 'Example Title');
}

But this doesn't show me anything on screen. Nothing, only the printing by console, but no notification, nor an error. Why?