Meterializecss- WordPress的下拉導航

我顯示的WordPress菜單項，但不顯示下拉菜單。如何顯示下拉菜單？Meterializecss- WordPress的下拉導航

的functions.php

register_nav_menus(array(
'primary' => __('Primary Menu', 'TNCTR-OnePage'),));

的header.php

<div class="navbar-fixed"> 
<nav class="navbar-tp"> 
    <div class="nav-wrapper"> 
    <div class="container"> 
    <a href="<?php bloginfo('url'); ?>" class="brand-logo logo"></a> 

    <?php 
    wp_nav_menu(array(
     'menu'  => 'primary', 
     'menu_class' => 'right hide-on-med-and-down' 

    )); 
    ?> 
<?php 
    wp_nav_menu(array(
     'menu'  => 'primary', 
     'menu_class' => 'side-nav', 
     'menu_id' => 'mobilemenu', 
     'items_wrap'  => '<ul id="slide-out" class="%2$s">%3$s</ul>' 
    )); 
    ?> 
    <a href="#" data-activates="slide-out" class="button-collapse"><i class="mdi-navigation-menu"></i></a> 
    </div> 
    </div> 
</nav>

HTML版本。 http://pasted.co/b2fc8b68

來源

2016-01-14 Yakup Seymen