getChatStatistics return error

[Orxan80dd]

i get authorization and try call method getChatStatistics
$tdlib->send([
'@type' => 'getChatStatistics',
'chat_id' => $chat_id,
'is_dark' => false,
]);
but get error {"@type":"error","code":400,"message":"Failed to parse JSON object as TDLib request: Unknown class "getChatStatistics""}