How to specify dates when requesting VK group statistics?

Question

PHP

Hello, I want to get statistics data, for example, from 04/21/2019 to 04/28/2019
I make the request as follows (I use the official library):

function show($data){
    print_r ("{$data}.<br>");
}
$date = "2019-04-21";
$now = date ("Y-m-d",time ());
echo strtotime ($date)."---".time ()."<br>";
$nd = $vk->stats ()->get($token,[
    "group_id"=>"000000000",
    "interval"=>"week",
    "timestamp_from" => strtotime ($date),
    "timestamp_to" => strtotime ($now),
    "stats_groups" => "visitors"

]);
print_r ("С ".date ("Y-m-d",$nd[0]["period_from"])."<br>");
print_r ("По ".date ("Y-m-d",$nd[0]["period_to"])."<br>");

show ("Всего просмотров за период: {$nd[0]["visitors"]['views']}");
show ("Всего посетителей за период: {$nd[0]["visitors"]['visitors']}");

print_r ($nd[0]);

As a result, I get:

If you remove the line "interval"=>"week" from the parameters, then you get the following:

Where 1555794000---1556438584 - date_from---date_now
What could be the problem? I honestly don't understand.
Who can faced it?