If your high school or diploma is missing in the anabin database, then this does not mean that they are not recognized in Germany. The anabin database is replenished on the basis of requests for diploma evaluation. So before you, no one has sent your university or diploma for evaluation. In order for a diploma to be recognized in Germany, you need to send it for evaluation to the Central Office for the Equivalence of Foreign Education (Zentralstelle für ausländisches Bildungswesen). If you found your university and diploma in the anabin database, but the university or diploma has an H+/- status, then in this case the diploma also needs to be sent to ZAB for evaluation.