validare data

[asdas]

<?php
$date= 12/05/2005;

list ($month, $day, $year) = explode ('/',$date);

if (checkdate($month, $day, $year)){
print "Data Valida";
}
else {
print "Data nn valida";
}

?>

Mi da queste notice... perche ?

Notice: Undefined offset: 2 in H:\webs\001095\test_data.php on line 4

Notice: Undefined offset: 1 in H:\webs\001095\test_data.php on line 4
DAta nn valida