Using is_page_template in an if statement

Hi trying to use the is_page_template function in my if statement but can’t get it to work

<?php $pageslug = $post->post_name;

          if ( ( ($pageslug == 'brochure-websites') || ($pageslug == 'template-websites') || ( is_page_template('single-portfolio.php') ) || ($pageslug == 'contact') ) ) { ?>								

  <div id="banner-small">

        </div><!--banner-small-->

         <div class="banner-footer"></div><!--end banner-footer-->

         <?php } ?>

The values using the pageslug work fine but the if statement does not work for the ( is_page_template(‘single-portfolio.php’) )

Any ideas?

Thanks