I followed the form tutorial to display a form for a new post. This does not display any of my fields. All it displays is the button to post a new item
<div id="primary">
<div id="content" role="main">
<?php acf_form(array(
'post_id' => 'new',
'field_groups' => array(4),
'submit_value' => 'Post a New Item'
)); ?>
</div><!-- #content -->
</div><!-- #primary -->