wp_nav_menu not outputting as expected from configuration

I’ve got a nav function in functions.php:

function html5blank_nav()
{
    wp_nav_menu(
    array(
        'theme_location'  => 'header-menu',
        'menu'            => '', 
        'container'       => false, 
        'menu_class'      => 'nav', 
        'menu_id'         => '',
        'echo'            => true,
        'fallback_cb'     => 'wp_page_menu',
        'before'          => '',
        'after'           => '',
        'link_before'     => '',
        'link_after'      => '',
        'items_wrap'      => '<ul class="%2$s">%3$s</ul>',
        'depth'           => 0,
        'walker'          => ''
        )
    );
}

And it’s called in header.php with:

<?php html5blank_nav(); ?>

And my output is:

<div class="nav">
  <ul>
    <li class="page_item page-item-2"><a href="http://localhost/?page_id=2">Sample Page</a></li>
    <li class="page_item page-item-4"><a href="http://localhost/?page_id=4">Test page</a></li>
  </ul>
</div>

But What I was trying to achieve was this structure:

<ul class="nav">
   <li><a href="http://localhost/?page_id=2">Sample Page</a></li>         
   <li><a href="http://localhost/?page_id=4">Test page</a></li>          
</ul>

I thought that setting container=false would get rid of the containing divs, and that setting menu_class=’nav’ would add the nav class to the ul as it states here: http://codex.wordpress.org/Function_Reference/wp_nav_menu

Why isn’t it recognising my settings?