Untitled

Weird issue with PHP's DateTime::add not adding time
<?php
$item = array('monthly_on_the' => 4);
$date = new DateTime();
$date->modify('first day of this month');
print_r($date);
$interval = new DateInterval('P'.$item['monthly_on_the'].'D');
print_r($interval);
$return = $date->add($interval);
if (!$return) die('Bad stuff happened!');
print_r($date);

DateTime Object
(
    [date] => 2012-02-01 17:15:23
    [timezone_type] => 3
    [timezone] => Australia/Sydney
)
DateInterval Object
(
    [y] => 0
    [m] => 0
    [d] => 4
    [h] => 0
    [i] => 0
    [s] => 0
    [invert] => 0
    [days] =>
)
DateTime Object
(
    [date] => 2012-02-01 17:15:23
    [timezone_type] => 3
    [timezone] => Australia/Sydney
)

$date->setTimestamp(strtotime('first day of this month', $date->getTimestamp()));