Форуми / Cotonti / Extensions / Support / Data to TPL with AJAX question

I'm trying to get data into a TPL from a PHP file with AJAX.

The code I currently have is as following:

This is the JavaScript bit:

$(document).ready(function() {
    function updateTesting(){
        ajaxSend({
            method: "GET",
            url: 'index.php?r=test&a=update',
            data: "",
            divId: 'test_div'
        });
    }
    updateTesting();

And test.ajax.php:

if ($a == 'update') {
	foreach ($res->fetchAll() as $row) {
		$t->assign(array(
			'TEST_USERNAME' => cot_build_user($row['test_userid'], htmlspecialchars($row['test_username'])),
			'TEST_MESSAGE' => cot_parse($row['test_message'], $cfg['plugin']['comments']['markup']),
			'TEST_DATE' => cot_date('M jS', $row['test_date']),
			'TEST_DATETIME' => cot_date('G:i', $row['test_date'])
		));
		$t->parse('MAIN.TEST_ROW');
	}
}

The TPL:

<!-- BEGIN: MAIN -->

<div id="test_div">
<!-- BEGIN: TEST_ROW -->
	{TEST_USERNAME}
	{TEST_MESSAGE}
	{TEST_DATE}
	{TEST_DATETIME}
<!-- END: TEST_ROW -->
</div>

<!-- END: MAIN -->

For some reason it just doesn't display what I assign to MAIN.TEST_ROW.
What am I missing here?

When I do a simple echo for testing like shown below it does output the data in the TPL with AJAX.

if ($a == 'update') {
	foreach ($res->fetchAll() as $row) {
		echo $row['test_message'];
	}
}

Thanks.

Added 1 hours later:

Hmm, it sort of works when I add to the foreach loop both parse and out:

$t->parse('MAIN.TEST_ROW');
$t->out('MAIN.TEST_ROW');

But I'm wondering if this is the correct way?

Added 2 days later:

Bump.