Using Filters on a Find

Hi everyone,

I’m searching the web for several hours but could not figure out whats wrong.
All c# examples are exactly the same like in my code.

        var settings = MongoClientSettings.FromConnectionString(mongodburi);
        var client = new MongoClient(settings);
        var _database = client.GetDatabase(mongodbname);
        var _collection = _database.GetCollection<BsonDocument>("Customers");
        var betterFilter = Builders<dataCustomer>.Filter.Eq(m => m.Nachname, this.Werte.Nachname);
           betterFilter &= Builders<dataCustomer>.Filter.Eq(m => m.Vorname, this.Werte.Vorname);
           betterFilter &= Builders<dataCustomer>.Filter.Eq(m => m.Geburtsdatum, this.Werte.Geburtsdatum);
        var customer = _collection.Find(betterFilter).ToList();


Schweregrad Code Beschreibung Projekt Datei Zeile Unterdrückungszustand
Fehler CS1503 Argument 2: Konvertierung von MongoDB.Driver.FilterDefinition<JN_Manager.dataCustomer> in System.Linq.Expressions.Expression<System.Func<MongoDB.Bson.BsonDocument, bool>> nicht möglich. JN-Manager A:\Daniel\APPS\C#\JN-Manager\JN-Manager\classes\customer.cs 882 Aktiv

Hope someone can help me out.

Thanks and best greets,