Other single template

Hi, I got a little code which display’s another single template than the default single.php if you’re viewing category 1.

<?php if ( in_category('1')) {include(TEMPLATEPATH.'/single-portfolio.php');
} else { ?>

But when I’m viewing a subcategory of category 1, it will display the default single.php instead of single-portfolio.php.

Hope you can help me, Steven.

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