Why is a message not sent in the bot for VK?

Question

PHP

Hello! I have a code for a Callback bot in PHP, I confirmed the server, but for some reason the bot does not want to respond to commands. Help me please.

The code:

<?php

$token = "REDACTED";

function vk_msg_send($peer_id,$text){
  $request_params = array(
    'message' => $text, 
    'peer_id' => $peer_id, 
    'access_token' => $token,
    'v' => '5.87' 
  );
  $get_params = http_build_query($request_params); 
  file_get_contents('https://api.vk.com/method/messages.send?'. $get_params);
}

$data = json_decode(file_get_contents('php://input'));

switch ($data->type) {  
  case 'confirmation': 
    echo "REDACTED"; 
  break;  
    
  case 'message_new': 
    $message_text = $data->object->text;
    $id = $data->object->peer_id;
    if ($message_text == "/start"){
      vk_msg_send($id, "OK");
    }
    echo 'ok';
  break;
}

?>