Json echoing empty data to AJAX - php

Question

After both sql commands are run, JSON should send an updated result to the AJAX script. Upon triggering, a spot opens in the page where the data should be populating, but nothing there. The PHP below is not creating any error messages and the data is updating to the db. I wish I had a more specific type of question but Im not finding the cause of the problem.
$storyidr=$_POST['storyidr'];
$mysqli = mysqli_connect($dbhost,$dbusername,$dbpasswd,$database_name) or die ("Couldn't connect to server.");
if (mysqli_connect_errno($mysqli))
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$sql = "INSERT INTO ratings (storyidr, rank, entry_date) VALUES ('$_POST[storyidr]','$_POST[value]',now());";
$sql .= "SELECT AVG(rank) AS avrank from ratings WHERE storyidr = $storyidr";
if($mysqli->multi_query($sql))
{
if ($result = $mysqli->store_result())
{
$data = mysqli_fetch_assoc($result);
$avrank = $data['avrank'];
if(is_null($avrank)){$avrank ="null";}
if(!$mysqli)
{
$arr = array ('status'=>'fail');
echo json_encode($arr);
}
else
{
echo json_encode($avrank);
}
exit;
}
}
AJAX
<script type ="text/javascript">
$('#products .rateit').bind('rated reset', function (e) {
var ri = $(this);
var value = ri.rateit('value');
var storyidr = ri.data('storyidr');
ri.rateit('readonly', true);
$.ajax({
url: '../rate.php',
data: { storyidr: storyidr, value: value },
type: 'POST',
success: function (data) {
$('#response').append('<li>' + data + '</li>');
},
error: function (jxhr, msg, err) {
$('#response').append('<li style="color:red">' + msg + '</li>');
}
});
});
</script>
html
<ul id="response">
</ul>