Yes I’ve tried that, it doesn’t look at the category ID between the brackets, it only looks at the is_attachment and checks if the page is an attachment.
I’ve also tried in_category.
<?php
if ( in_category('3') ) {
include(TEMPLATEPATH . '/francesidebar.php');
}
?>
For some reason this works fine on a single blog post on single.php, but not on image.php or attachment.php.