How do I get my AJAX to be asynchronous?

[Cap'n Steve]

The following code doesn't work, it runs before the response is received so everything is undefined. If you change the agent object to be synchronous (change the first line's true to false), it works fine.

function rateQuote(e, rating, quoteId) {
	agent = new vB_AJAX_Handler(true);
	agent.send('quotes.php', '&do=rate&ajax=y&quoteid=' + quoteId + '&vote=' + rating);

	if (checkAgentStatus()) {
		var results = agent.handler.responseText.split("\t");
		fetch_object('stats' + quoteId).innerHTML = quotes_phrase_total + ': ' + results[0] + ' - ' + quotes_phrase_votes + ': ' + results[1] + ' - ' + quotes_phrase_average + ': ' + results[2];
		fetch_object('rating' + quoteId).innerHTML = quotes_phrase_you_rated_this + results[3];
		do_an_e(e);
	}
}