Listing baby pages, exclude the present web page

I am attempting to show the kid pages of a father or mother web page, that is working. However after I tried to exclude the present web page within the record the place the kid pages displayed, it is not working.

Tips on how to repair this?

$current_post_id = $post->ID;
if(wp_list_pages("title_li=&child_of=2143&exclude='.$current_post_id.'")):
    if($title)
        echo $before_title . $title . $after_title;
        wp_list_pages("title_li=&child_of=2143&exclude='.$current_post_id.'");
endif;