pagination issue

<?php get_header(); ?>
<!--<p>archive-questions.php</p>-->
<!-- Left Nav -->
<nav class="alignLeft">
    <?php include @ ("leftnav.php"); ?>
</nav>
<div id="contentContainer" class="alignLeft">
    <div class="twoThirdsColumn alignLeft"> <!-- Center Column -->
        <div class="colTopHeader">
            <h2>Best Questions</h2>
            <div class="clear"></div>
        </div>

<?php
        $paged = get_query_var('paged');
        $wp_query = new WP_Query(array(
        'post_type' => 'questions',
        'posts_per_page' => 8,
        'paged' => $paged
    ));
        while ($wp_query->have_posts()) : $wp_query->the_post();
?>

    <div id="post-<?php the_ID(); ?>" <?php post_class(); ?>>
        <?php the_title('<h2 class="entry-title"><a href="' . get_permalink() . '" title="' . the_title_attribute('echo=0') . '" rel="bookmark">', '</a></h2>'); ?>
        <span class="pubDate"><?php the_time('F j, Y  ');?><?php echo get_the_term_list( $post->ID, 'postauthor', ' ', ', ', '' ); ?></span>

        <?php if ( has_post_thumbnail() ) { ?>
            <div class="alignLeft postThumb">
                <?php the_post_thumbnail('thumbnail'); ?>
            </div>
            <?php } ?>
        <?php the_excerpt(); ?>
    </div>

    <?php endwhile; ?>

<div class="navigation">
    <div class="alignLeft next-posts"><?php next_posts_link('&laquo; Older Questions', 0); ?></div>
    <div class="alignRight prev-posts"><?php previous_posts_link('Earlier Questions &raquo;', 0); ?></div>
<div class="clear"></div>
</div>

</div>

<div class="oneThirdColumn alignLeft"> <!-- Rigth Column -->
    <div class="colTopHeader">
        <h2>Share A Question</h2>
        <div class="clear"></div>
    </div>

    <!-- Quick Post for Best Questions -->
    <?php dynamic_sidebar( 'first-footer-widget-area' ); ?>


    <div class="colTopHeader">
        <h2>Filter Best Questions</h2>
        <div class="clear"></div>
    </div>

    <!-- Faceted Search -->
    <?php dynamic_sidebar( 'secondary-widget-area' ); ?>
</div>
</div>
<?php get_footer(); ?>