title: Wordpress wp_nav_menu not displaying menu
body: <p>I'm using the following code to display the menu on a site. Its a Network and it works on the Root site but when I create a new network it doesn't work</p>
  
  <pre><code>&lt;?php wp_nav_menu( array( 'theme_location' =&gt; 'header-menu','menu_class'      =&gt; 'top-nav') ); ?&gt;
  </code></pre>
  
  <p>The only thing it echos out is</p>
  
  <pre><code>class="last-menu-item menu-item-footer-main-container"&gt;
  </code></pre>
  
  <p>nothing else. Any idea what may be causing this?</p>
  
  <p>edit: surrounding code</p>
  
  <pre><code>&lt;div id="header"&gt;
  
  
  
  &lt;?php wp_nav_menu( array( 'theme_location' =&gt; 'header-menu','menu_class'      =&gt; 'top-nav') ); ?&gt;
  
      &lt;/div&gt;&lt;!-- end #header --&gt;
  </code></pre>
  
  <p>surrounding output:</p>
  
  <pre><code>            &lt;div id="header"&gt;
  class="last-menu-item menu-item-header-menu-container"&gt;&lt;ul id="menu-header-menu" class="top-nav"&gt;&lt;li id="menu-item-7" class="first-menu-item menu-item menu-item-type-post_type menu-item-object-page current-menu-item page_item page-item-5 current_page_item menu-item-7"&gt;&lt;a href="#"&gt;...&lt;/a&gt;&lt;/li&gt;
  &lt;/ul&gt;&lt;/div&gt;
  </code></pre>