lonchbox on "wp_nav_menu exclude post or page by ID"

Hi,

I know there is any mention to exclude parameter for wp_nav_menu in the codex, but also found some posts saying this is posible, I try many of it and don´t work.

In my case I´m creating a custom widget for my theme, and this widget shows custom menu, what I want is if is in a page which are listed in the menu the item of this page was remove form the menu, so first I get the ID and I use this variable in the exclude.

<?php
			global $wp_query;
			$page_id = $wp_query->post->ID;
		?>
		<!--BEGIN #joinn-us-->
			<aside id="related-content" class="widget panel">
				<h4 class="widget-title"><?php _e('Related Content','udla'); ?></h4>

				<?php wp_nav_menu( array(
					'theme_location'=> 'related-menu',
					'menu_class'	=> 'side-nav',
					'container'		=> '',
					'container_class'	=> '',
					'exclude' => $page_id
				) ); ?>
			</aside>
		<!--END #join-us-->

Should I use the fallback_cb parameter?
Or do I need to set a function to use this parameter?

Thanx for any help.