SQL #1064 Syntax Error or Access Violation

I created a website by myself and I have an error that I can not find. Yet in another page of my site, the method works. Do you see the problem ?

I compared with the other code that works and I don't see the problem.

// In this part, before I had a fatal error because of PDO.
$req = $bdd->prepare('SELECT id, pseudo FROM members WHERE username = ?');
// I added this line to solve the error with PDO.
$member_infos = $req->fetch(PDO::FETCH_ASSOC);

$id_member = $member_info['id'].'-'.$membre_info['username'];

// The part of the code with the SQL syntax error
$creat_collection = $bdd->query('INSERT INTO ad, at (id_members) VALUES ('.$id_member.')');

I have the error :

Fatal error: Uncaught PDOException: SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near ' at (id_members) VALUES (17-test)' at line 1 in C:\xampp\htdocs\creation.php:35 Stack trace: #0 C:\xampp\htdocs\creation.php(35): PDO->query('INSERT INTO ad,...') #1 {main} thrown in C:\xampp\htdocs\creation.php on line 35

I put a echo after the code to be sure it work, but he isn't display.