I know there is a lot of questions about this but I really don\'t know where is my mistake.
My service is registered in the AndroidManifest.xml file
As in documentation, PendingIntent.getBroadcast() is used to retrieve a PendingIntent that will perform a broadcast, like calling Context.sendBroadcast().
You need to call PendingIntent.getService() instead, which will start IntentService:
PendingIntent pending = PendingIntent.getService(this, 0, alarmIntent, 0);