Display images from different folders - php

Question

using external web pages customers can create a ticket with different values and upload images. All these values are passed to an internal system that allows people to manage the tickets but are shown only the database values and not the images on a simple php page. When a ticket is created the ticket and the images folder (that is automatically created) share a common and unique ID. So the ticket is the same as the folder name.Searching for the ID the pages with all the data is shown using this:
<?php
$link = mysqli_connect("xxx", "xxx", "xxx", "xxx");
if($link === false){
die("ERRORE: DB error. " . mysqli_connect_error());
}
$num = $_GET['ticket_id'];
$query = "SELECT * FROM tickets WHERE ticket_id = '$num'";
$result = mysqli_query($link,$query);
$row = mysqli_fetch_array($result);
?>
<form action="edit.php" method="post">
<table id="myTable">
etc
I tried using something like glob function but I always get "no images to display"
<?php $thumbs = glob("2021/ticket_att/$num/*.{jpg,jpeg,png,gif}", GLOB_BRACE)?>
<?php
if(count($thumbs)) {
natcasesort($thumbs);
foreach($thumbs as $thumb) {
?>
<li>
<img src="<?php echo $thumb ?>" width="50%" alt="ticket image" />
</li>
<?php
}} else {
echo "No images to display!";
}
?>
Where am I getting wrong?
Thank you!
--> UPDATE <--
The glob function works if I change the value of $num into a fixed value (for example
<?php $thumbs = glob("2021/ticket_att/123456/*.{jpg,jpeg,png,gif}", GLOB_BRACE)?>
but if I check the value of $num is correct. Maybe the functions doesnt' read a variable value?
Thanks!