Sub pages: custom sidebar

Hi,

I have a theme with a sidebar for every kind of page, tag and categories. Now I have sub pages and I have put this code in the sidebar.php

<?php if(is_page(‘2190’)){ ?>

But nothing is shown in the subpage. I have search and I have found another solutions, like

<?php if($post->post_parent =’2190′){ ?>

Then I can see the custom sidebar in the subpage and I have two sidebars in the rest of the blog: the original for every tag, category and pages, and at the end of this one, the custom sidebar of the subpage… Any idea? Thanks!