Hvorfor kan jeg ikke liste filer?

<?php
$conn_id = ftp_connect("xxx.dk");
$login_result = ftp_login ($conn_id, "user", "psw");

if ((!$conn_id) || (!$login_result)) {
      echo "Ftp-connect failed!"; die;
  } else {
      echo "Connected.<br>";
  }
 

if (ftp_chdir($conn_id, "public_html")) {
  echo "Current directory is now: " . ftp_pwd($conn_id) . "\n";
} else {
  echo "Couldn't change directory\n";
}
$buff = ftp_rawlist($conn_id, '/');
var_dump($ftp_rawlist);

ftp_pasv ($conn_id, true) ;

ftp_quit($conn_id);

?>