wp_list_pages

Hi there,
I have the following code:

<?php
if (is_page(40) || $post->post_parent == '40' || in_category('3')) {
echo '<ul class="subnav">';
wp_list_pages('title_li=&child_of=54&sort_column=menu_order');
echo '</ul>';
} //end ?>

Problem ?

The page with id ’40’ (as specified) – only displays the list when I add the ‘in_category(‘3’) … why is that?

If i simply put

<?php
if (is_page(40)) {
echo '<ul class="subnav">';
wp_list_pages('title_li=&child_of=54&sort_column=menu_order');
echo '</ul>';
} //end ?>

the list will not display itself on page…

Any help / insight is well appreciated!