递归解析功能

Question

I made a function that parses a certain page of a website(a forum thread). It should select users and their posts and then go on to the next page and do the same. While it does that, its return value is always null. I think I made a mistake with the recursion, but can't really figure it out.

Here is the function, I made it return only the userlist, for now.

function getWinners( $thread,$userlist,$postlist ) {
    //libxml_use_internal_errors(true);
    $html = file_get_html( $thread );


    //get users
    $users=$html->find( 'li[class="postbitlegacy postbitim postcontainer old"] div[class=username_container] strong span' );
    foreach ( $users as $user )
        //echo $user . '<br>';
        array_push( $userlist, $user );
    //get posts
    $posts=$html->find( 'li[class="postbitlegacy postbitim postcontainer old"] div[class=postbody] div[class=content]' );
    foreach ( $posts as $post )
        // echo $post . '<br>';
        array_push( $postlist, $post );
    //check if there is a next page
    if ( $next=$html->find( 'span[class=prev_next] a[rel="next"]', 0 ) ) {
        $testa='http://forums.heroesofnewerth.com/'.$next->href;
        // echo $testa. '<br>';
        $html->clear();
        unset( $html );

        //recursive calls until the last page of the forum thread
        getWinners( $testa,$userlist,$postlist );

     //no more thread, return users
    }else return $userlist;
}

And the call

$thread='http://forums.heroesofnewerth.com/showthread.php?553261';

    $userlist=array();
    $postlist=array();

 $stuff=getWinners( $thread,$userlist,$postlist);
 echo $stuff[0];

Here, stuff is empty.