Fehler beim vor- bzw zurückblättern

<div id="posts" class="">
    <?php
    if (get_option('purephoto_thumbs_width')) {
        $thumbwidth = get_option('purephoto_thumbs_width');


        $thumbheight = ($thumbwidth * 3) / 4;
        $thumbheight = floor($thumbheight);


        if (get_option('purephoto_thumbs_height')) {
            $thumbheight = get_option('purephoto_thumbs_height');
        }
    }


if(get_option( PPTNAME.'_doublecategories' ) == 'yes') {
$cat = get_option(PPTNAME.'_categories');
    query_posts('cat=-'.$cat );
}


    if (have_posts()):while (have_posts()) : the_post();
            ?>
            <div id="post-<?php the_ID(); ?>"  <?php post_class('thumb'); ?>>
                <a href="<?php the_permalink() ?>" class="thumb-link">
                    <?php
                    if (!post_password_required())  {
                        if (has_post_thumbnail()) {
                            the_post_thumbnail('homepage-thumb');
                        } else {
                                $id = $post->ID;
                                $order=  get_post_meta($post->ID, "galleryorder_value", $single = true);
                                $exclude = get_post_meta($post->ID, "galleryexlude_value", $single = true);
                                $first_img = get_first_image_url2($id,$order,$exclude);
                            ?>
                            <img src="<?php  bloginfo('template_directory'); ?>/backend/timthumb.php?src=<?php  echo $first_img ?>&h=<?php echo $thumbheight;  ?>&w=<?php echo $thumbwidth; ?>&zc=1" width="<?php  echo $thumbwidth; ?>" height="<?php echo $thumbheight; ?>"  />
                        <?php
                        }
                    } else {
                        ?>
                        <img src="<?php bloginfo('template_url') ?>/img/locked.png"  />
            <?php } ?>
                </a>
                <h2>
                    <a href="<?php the_permalink() ?>"  rel="bookmark" title="Permanent Link to <?php the_title();  ?>"><?php the_title(); ?></a>
                </h2>
            </div><?php /* end post */ ?>


    <?php endwhile; ?>
<?php else : ?>
        <h2 class="page_header center">Not Found</h2>
        <div class="entry">
            <p>Sorry, but you are looking for something that isn't here.</p>
        </div>
    <?php endif; ?>
    <div class="clear"> </div>
    <?php if (function_exists('wp_pagenavi')) { // if expirimental feature is active  ?>
        <?php wp_pagenavi(); ?>
    <?php } else { // if it is disabled, display regular wp prev & next links  ?>
        <?php
        $prev_link = get_next_posts_link(__('Older Entries'));
        $next_link = get_previous_posts_link(__('Newer Entries'));


        if ($prev_link || $next_link) {
            ?>
            <div class="posts-navigation">
        <?php if ($next_link) { ?>
                    <div id="next_post">
                        <p><?php echo $next_link ?></p>
                    </div>
        <?php } if ($prev_link) { ?>
                    <div id="prev_post">
                        <p><?php echo $prev_link ?></p>
                    </div>
            <?php } ?>
            </div>
    <?php } ?>
<?php } ?>
</div> <!-- eof: #post -->