oci_fetch always return false

Question

I've made this PHP code :

$sql = 'SELECT FIRST_NAME, LAST_NAME FROM journalists WHERE category = :cat ';
$requete = oci_parse($identifiants, $sql);
oci_bind_by_name($requete, 'cat', $_GET['cat']);
oci_execute($requete);
var_dump(oci_fetch($requete));

Before make a loop, I wanted to check if the request is correctly executed. But the var_dump() always return false. So, I have tried to make the request manually in Toad for Oracle with the parameter '1' and it works correctly !

So I don't understand what in my code fails.

Anyone have an idea ?

Thanks in advance