Creator map for class MongoDB.Bson.IO.BsonDocumentWriter has 2 arguments, but none are configured. help

i’m trying to create a a document from a class created runtime.

let me show what i have

this is my classes

public class BsonFile
    public BsonEntry[] _entries;

public class BsonEntry
    public string _classID {get; set;}
    public Dictionary<string,BsonArray> _dictionary {get; set;}

and this is what i do

    BsonFile file = 
    new BsonFile();
    file._entries =
    var entry = file.ToBsonDocument();
    var bson =  BsonDocument.Create(entry);

where _propDic is contains the array of BsonEntry that will be stored in the BsonFile class.

what i’m doing wrong?