URL wird nicht korrekt angegeben

function top_trackbacks_jahr() {
    global $wpdb;
    $toptrack_query="SELECT comment_ID, comment_date, DATE_FORMAT(comment_date, '%d.%m.%Y') AS comment_date_ger, comment_post_ID, SUBSTRING_INDEX(REPLACE( comment_author_url, 'www.', '' ) , '/', 3) as top_track, COUNT(*) as top_num FROM $wpdb->comments
        WHERE comment_approved='1'
        AND comment_type IN('trackback', 'pingback')
        AND comment_date >= CURDATE() - INTERVAL 365 DAY
        AND comment_author_url NOT LIKE 'http://domain.de%'
        AND comment_author_url != ''
        AND comment_author_url NOT LIKE 'http://twitter.com%'
        GROUP BY top_track
        Order by top_num DESC, comment_date DESC
        LIMIT 3";
    $toptrack_result = $wpdb->get_results($toptrack_query);
    if ( !empty($toptrack_result) ) {
        echo '<ul>';
        foreach ($toptrack_result as $comment) :
            $post = get_postdata($comment->comment_post_ID);
            $tb_aut = $comment->top_track;
            $tb_aut = str_ireplace("http://", "", $tb_aut);
            echo '<li style="list-style-type:none"><br /><a href="'.$comment->top_track.'/" title="'.$comment->top_track.'"target="_blank">'.$tb_aut.'</a> ('.$comment->top_num.')<br />zuletzt am '.$comment->comment_date_ger.' in:<br /><a href="http://themenfreund.de/'. $post['Title'] .'" title="'.$post['Title'].'">'.$post['Title'].' </a></li>';
        endforeach;
        echo '</ul>';
    }
}