Problem with next_posts_link in custom query

Hi,
i have made a wordpress template with a Custom Select Query but i can’t see the next_posts_link don’t work, the next page is equal to the first page, why ?

here you can read my Custom Select Query:

<?php

$querystr = “
SELECT wposts.*
FROM $wpdb->posts wposts
LEFT JOIN $wpdb->postmeta wpostmeta ON wposts.ID = wpostmeta.post_id

WHERE wpostmeta.meta_key = ‘Scadenza’
AND wpostmeta.meta_value >= CURDATE()
ORDER BY wpostmeta.meta_value ASC
LIMIT 10
“;

$pageposts = $wpdb->get_results($querystr, OBJECT);

?>

<?php if ($pageposts): ?>
<?php foreach ($pageposts as $post): ?>
<?php setup_postdata($post); ?>