Faulty RSS output

<pre class="cake-error"><a href="javascript:void(0);" onclick="document.getElementById('cakeErr4fa859a50ce1d-trace').style.display = (document.getElementById('cakeErr4fa859a50ce1d-trace').style.display == 'none' ? '' : 'none');"><b>Warning</b> (512)</a>: Method RssHelper::header does not exist [<b>CORE/Cake/View/Helper.php</b>, line <b>179</b>]<div id="cakeErr4fa859a50ce1d-trace" class="cake-stack-trace" style="display: none;"><a href="javascript:void(0);" onclick="document.getElementById('cakeErr4fa859a50ce1d-code').style.display = (document.getElementById('cakeErr4fa859a50ce1d-code').style.display == 'none' ? '' : 'none')">Code</a> <a href="javascript:void(0);" onclick="document.getElementById('cakeErr4fa859a50ce1d-context').style.display = (document.getElementById('cakeErr4fa859a50ce1d-context').style.display == 'none' ? '' : 'none')">Context</a><pre id="cakeErr4fa859a50ce1d-context" class="cake-context" style="display: none;">$this	=	object(RssHelper) {}
$method	=	'header'
$params	=	array()</pre><pre class="stack-trace">Helper::__call() - CORE/Cake/View/Helper.php, line 179
RssHelper::header() - [internal], line ??
include - APP/View/Layouts/rss/default.ctp, line 2
View::_evaluate() - CORE/Cake/View/View.php, line 908
View::_render() - CORE/Cake/View/View.php, line 872
View::renderLayout() - CORE/Cake/View/View.php, line 527
View::render() - CORE/Cake/View/View.php, line 471
Controller::render() - CORE/Cake/Controller/Controller.php, line 959
Dispatcher::_invoke() - CORE/Cake/Routing/Dispatcher.php, line 110
Dispatcher::dispatch() - CORE/Cake/Routing/Dispatcher.php, line 85
[main] - APP/webroot/index.php, line 97</pre></div></pre><rss version="2.0"><channel><title>Our Current Posts</title><link>http://localhost:8888/posts.rss</link><description>View the most recent posts from our cakephp blog</description><language>en-us</language><item><title>The title</title><link>http://localhost:8888/posts/view/1</link><guid>http://localhost:8888/posts/view/1</guid><description>This is the post body.</description><pubDate>Sat, 05 May 2012 02:22:06 -0400</pubDate></item><item><title>A title once again</title><link>http://localhost:8888/posts/view/2</link><guid>http://localhost:8888/posts/view/2</guid><description>And the post body follows.</description><pubDate>Sat, 05 May 2012 02:22:06 -0400</pubDate></item><item><title>Title strikes back</title><link>http://localhost:8888/posts/view/3</link><guid>http://localhost:8888/posts/view/3</guid><description>This is really exciting! Not.</description><pubDate>Sat, 05 May 2012 02:22:06 -0400</pubDate></item><item><title>Test</title><link>http://localhost:8888/posts/view/5</link><guid>http://localhost:8888/posts/view/5</guid><description>This is the first test.</description><pubDate>Sat, 05 May 2012 17:59:09 -0400</pubDate></item></channel></rss>