JSON working one place but not another - php

Question

I'm redesigning my site to base it off WordPress, and in the process, I need to import some PHP/jQuery. I find that it works fine on the original page but not the new one.
Here are the results of the JSON dumps:
Old - empty as it should be because no data
New - doesn't like using $_POST['club'] to import
The code in both instances is:
<script type="text/javascript">
$(document).ready(function() {
$.ajax({
type: "post",
url: "eventinfo.php",
data: $('#club').serialize(),
success: function(data) {
$('#right_inside').html('<h2>' + $('#club').val() + '<span style="font-size: 14px"> (' + data[0].day + ')</h2><p>Entry: ' + data[0].entry + '</p><p>Queue jump: ' + data[0].queuejump + '</p><p>Guestlist closes at ' + data[0].closing + '</p>');
},
dataType: "json"
});
});
$('#club').change(function(event) {
$.ajax({
type: "post",
url: "eventinfo.php",
data: $(this).serialize(),
success: function(data) {
$('#right_inside').hide().html('<h2>' + $('#club').val() + '<span style="font-size: 14px"> (' + data[0].day + ')</h2><p>Entry: ' + data[0].entry + '</p><p>Queue jump: ' + data[0].queuejump + '</p><p>Guestlist closes at ' + data[0].closing + '</p>').fadeIn('500');
},
dataType: "json"
});
});
</script>
And my eventinfo.php is:
<?php
header('Cache-Control: no-cache, must-revalidate');
header('Expires: Mon, 26 Jul 1997 05:00:00 GMT');
header('Content-type: application/json');
include('guestvibe_functions.php');
connect();
$night = $_POST['club'];
$night = mysql_real_escape_string($night);
$query = "SELECT * FROM nights WHERE name = '" .$night. "'";
$result = mysql_query($query);
$items = array();
if($result && mysql_num_rows($result) > 0) {
while ($row = mysql_fetch_array($result)) {
$items[] = array("entry"=>$row['entry'], "day"=>getLongDateString($row['day']), "queuejump"=>$row['queue jump'], "closing"=>$row['closing']);
}
}
mysql_close();
// convert into JSON format and print
echo json_encode($items);
?>
It's late so I hope I've explained this alright. Any ideas what's wrong?
EDIT
I should add that both are on the same server / hosting plan. The new one is just one directory up.

Answer 1

see this answer for clues
I think you probably have either a newer version of PHP or different server settings on the new PHP server.

Answer 2

I see two possibilities.
The first is that on the new site the club= variable is not populated by AJAX when in the old site it is. Then you must discover why the serialize() does not include a variable called 'club'.
The second is that the club= variable wasn't necessarily populated even in the old site, and you just didn't get the notice warning.
In this case, modifying the code from
$night = $_POST['club'];
in
$night = isset($_POST['club']) ? $_POST['club'] : '';
should solve the problem.
UPDATE
I checked the site, but the eventinfo URL I received is different from the one you quote. What my Firefox got was:
http://www.guestvibe.com/wordpress/eventinfo.php
...which results in a 404 Error.