페이징 숫자는 제대로 나오는데, 왜 숫자를 클릭하면 아무 반응도 없을까요?

[ itemuse.php ]

function itemuse_page($write_pages, $cur_page, $total_page, $url, $add="")
{
    //$url = preg_replace('#&page=[0-9]*(&page=)$#', '$1', $url);
    $url = preg_replace('#&page=[0-9]*#', '', $url) . '&page=';

    $str = '';
    if ($cur_page > 1) {
        $str .= '<a href="'.$url.'1'.$add.'" class="pg_page pg_start" style="margin-right:15px">first</a>'.PHP_EOL;
    }

    $start_page = ( ( (int)( ($cur_page - 1 ) / $write_pages ) ) * $write_pages ) + 1;
    $end_page = $start_page + $write_pages - 1;

    if ($end_page >= $total_page) $end_page = $total_page;

    if ($start_page > 1) $str .= '<a href="'.$url.($start_page-1).$add.'" class="pg_page pg_prev" style="margin-right:15px">prev</a>'.PHP_EOL;

    if ($total_page > 1) {
        for ($k=$start_page;$k<=$end_page;$k++) {
            if ($cur_page != $k)
                $str .= '<a href="'.$url.$k.$add.'" class="pg_page" style="margin-right:15px">'.$k.'</a><span class="sound_only">페이지</span>'.PHP_EOL;
            else
                $str .= '<span class="sound_only">열린</span><strong class="pg_current" style="margin-right:15px">'.$k.'</strong><span class="sound_only">페이지</span>'.PHP_EOL;
        }
    }

    if ($total_page > $end_page) $str .= '<a href="'.$url.($end_page+1).$add.'" class="pg_page pg_next" style="margin-right:15px">next</a>'.PHP_EOL;

    if ($cur_page < $total_page) {
        $str .= '<a href="'.$url.$total_page.$add.'" class="pg_page pg_end">last</a>'.PHP_EOL;
    }

    if ($str)
        return "<nav class=\"pg_wrap\"><span class=\"pg\">{$str}</span></nav>";
    else
        return "";
}

[ itemuse.skin.php ]

<div>
<?php
echo itemuse_page(5, $page, $total_page, "./itemuse.php?it_id=$it_id&page=");
?>
</div>