use different single template per category

Hello, would I like to know if someone created different single.php for every category?
I am using a theme, which calls bp-columns, and copy the following code is in my single.php:

<?php
$post = $wp_query->post;
if (in_category('25')) {
include(TEMPLATEPATH.'/single25.php');
}   elseif (in_category('64')) {
include(TEMPLATEPATH.'/single64.php');}
    elseif (in_category('128')) {
include(TEMPLATEPATH.'/single128.php');}
    else {include(TEMPLATEPATH.'/single-original.php');
    }
    ?>

In the same directory, I have these .php.
The problem is that when I deposit a post with id 25 for example, the screen stays in white and does not load anything.
Does someone know to which it owes?