boss_db:find works not correctly with indexed field (mongodb)

[kutu]

message model

-module (message, [Id, Message, CreationTime]).

40 seconds screencast

also cannt do right query for "id" field

boss_db:find(message, [], 5, 0, id, num_descending). % just first five entries (w/o sort)
boss_db:find(message, [], 5, 0, '_id', num_descending). % same as for creation_time