Frankly, I'm flummoxed. Can anyone tell me why I would get a failure message with this code?

$date = Zend_Date::now();
$date = $date->getIso();

if(Zend_Date::isDate($date, Zend_Date::ISO_8601)) {
    print('success');
} else {
    print('failure');
}

exit;

It also fails if I just pass in a Zend_Date object.

UPDATE:

a var_dump of the initial $date object looks like this:

object(Zend_Date)#107 (8) { ["_locale:private"]=> string(5) "en_US" ["_fractional:private"]=> int(0) ["_precision:private"]=> int(3) ["_unixTimestamp:private"]=> int(1257508100) ["_timezone:private"]=> string(14) "America/Denver" ["_offset:private"]=> int(25200) ["_syncronised:private"]=> int(0) ["_dst:protected"]=> bool(true) }

And a var_dump of the $date string after calling $date->getIso() looks like this:

string(25) "2009-11-06T04:48:20-07:00"

I am using ZF 1.9.5 on PHP 5.2.8. I am using XAMPP for Windows too if that makes a difference.