Single.php not responding to comment.php

Well, the single.php file doesn’t seem to be responding to the comment template as such… if I change or edit anything on the comment file (such as change headers, add a break etc.) nothing happens, but on the other hand if the
<?php comments_template( '', true ); ?>
isn’t included the comments disappear. The site is frodshamweb.co.uk/blog/post-5/

Thanks in advance