API ISPConfig: How to update a Client

Hello, i want to update the data of a client in ISPConfig width the API. But i can't work it.

Mi code is:

$client = new SoapClient(null, array('location' => $soap_location,'uri' => $soap_uri, 'trace' => 1, 'exceptions' => 1));

$session_id = 0;

try {
if($session_id = $client->login($username,$password)) {
$client_record = $client->client_get_by_username($session_id, $userCliente);
if (isset($client_record["client_id"])) {
$c_id = $client_record["userid"];
$client_record["city"] = "ZZZ";
$affected_rows = $client->client_update($session_id, $c_id, $reseller_id, $client_record);
}
}
}
catch(Exception $e){
echo "ERROR";
}

How i can update o change the information of the client? This code do anything.

Thank you.