I'm just trying to find out an account's disk usage and quota, so I'm trying the php xmlapi with this code, but it just gives a blank screen.

PHP Code:
include('xmlapi.php');

$user = "myaccount";
$password = "mypassword";
$ip = "123.345.567.789";  //the account IP address

$xmlapi = new xmlapi($ip);
$xmlapi->set_port(2083);
$xmlapi->password_auth($user, $password);
$xmlapi->set_debug(1);
print $xmlapi->api2_query($user, 'StatsBar', 'stat', 'display=diskusage');
print $xmlapi->accountsummary($user); 
As you can see there are two calls at the bottom -- neither returns anything. Anyone see anything wrong with this code? Also, does the account have to have the X3 theme, or can it have the X theme?