Styling custom menus

I have styled a vertical menu. When I try to use the menu’s css in my theme’s custom menu all the styling is removed.

Here is my theme code:

<nav class=”grid_3″>
<?php wp_nav_menu( array( ‘theme_location’ => ‘side-menu’, ‘menu_class’ => ‘mymenuclass’ ) ); ?>
</nav>

and I have registered in functions.php

function register_my_menus() {
register_nav_menus(
array(
‘top-menu’ => __( ‘Top Menu’ ),
‘side-menu’ => __( ‘Side Menu’ )
)
);
}
add_action( ‘init’, ‘register_my_menus’ );

Why is ‘mymenuclass’ being ignored by wp?