Глобальная переменная PHP — невозможно назначить новые значения

Этот код предназначен для бота Telegram.
Я пробовал глобальные переменные, но по некоторым причинам он не хранит значения.
Я объявил переменные вне функций, а затем объявил переменные глобальными внутри, но я не могу назначить новое значение. Они все еще вернули начальное значение, которое я ввел.

Что я сделал не так?

  $title=9; $cat=8; //to test global variable
function processMessage($message) {
global $title, $cat; //declaring global
// process incoming message
$message_id = $message['message_id'];
$chat_id = $message['chat']['id'];
$sender_id = $message['from']['id'];
$sender_first_name = $message['from']['first_name'];
$sender_last_name = $message['from']['last_name'];
$message_date = $message['date'];

if (isset($message['text'])) {
// incoming text message
$text = $message['text'];

//when user starts the bot
if (strpos($text, "/start") === 0) {
apiRequestJson("sendmessage", array('chat_id' => $chat_id, "text" => 'Please select an option:', 'reply_markup' => array(
'keyboard' => array(array('Category Check', 'Uncategorized')),
'one_time_keyboard' => false,
'resize_keyboard' => true)));

}

//category check that returns news title and category question to user
else if ($text === "Category Check") {

//MySQL Connection Details
$servername = "localhost";
$username = "user";
$password = "pass";
$dbname = "dbname";
$conn = new mysqli($servername, $username, $password, $dbname);

$sql = "SELECT * FROM `newsdata` WHERE `nb_count` OR `svm_count` <> 0 ORDER BY RAND() LIMIT 1 ";

$row = $result->fetch_assoc();

$nb_business = $row["nb_business"];
$nb_entertainment = $row["nb_entertainment"];
$nb_health = $row["nb_health"];
$nb_politics = $row["nb_politics"];
$nb_science = $row["nb_science"];
$nb_technology = $row["nb_technology"];
$nb_world = $row["nb_world"];
$svm_business = $row["svm_business"];
$svm_entertainment = $row["svm_entertainment"];
$svm_health = $row["svm_health"];
$svm_politics = $row["svm_politics"];
$svm_science = $row["svm_science"];
$svm_technology = $row["svm_technology"];
$svm_world = $row["svm_world"];
$title=$row["title"]; //assigning title
$nb_count=$row["nb_count"];
$svm_count=$row["svm_count"];

if($nb_business!=0)
{$cat='BUSINESS'; $track=1;}
else if ($nb_entertainment!=0)
{$cat='ENTERTAINMENT'; $track=1;}
else if ($nb_health!=0)
{$cat='HEALTH'; $track=1;}
else if ($nb_politics!=0)
{$cat='POLITICS'; $track=1;}
else if ($nb_science!=0)
{$cat='SCIENCE'; $track=1;}
else if ($nb_technology!=0)
{$cat='TECHNOLOGY'; $track=1;}
else if ($nb_world!=0)
{$cat='WORLD'; $track=1;}

else if ($svm_business!=0)
{$cat='BUSINESS'; $track=0;}
else if ($svm_entertainment!=0)
{$cat='ENTERTAINMENT'; $track=0;}
else if ($svm_health!=0)
{$cat='HEALTH'; $track=0;}
else if ($svm_politics!=0)
{$cat='POLITICS'; $track=0;}
else if ($svm_science!=0)
{$cat='SCIENCE'; $track=0;}
else if ($svm_technology!=0)
{$cat='TECHNOLOGY'; $track=0;}
else if ($svm_world!=0)
{$cat='WORLD'; $track=0;}
// output data of each row

//asking user if the category is correct
apiRequestJson("sendmessage", array('chat_id' => $chat_id, "text" => 'Is this news belongs to '.
$cat.' category? '.
$title.' '.$row["link"],
'reply_markup' => array(
'keyboard' => array(array('yes', 'no')),
'one_time_keyboard' => false,
'resize_keyboard' => true)));
}
//user answers
if ($text == "yes" || $text == "no"){
switch ($text) {
case "yes":
$nb_count=$nb_count--;
$svm_count=$svm_count--;
apiRequestJson("sendmessage", array('chat_id' => $chat_id, "text" => $cat.$title)); //broken here, output: 98

break;
case "no":
//dothat; break;
}