Twitter Feed not working

I have problem with Twitter Feed because it’s not working. There is a code which shows Twitter Feeds:

function grey_twitter_timeline( $id=NULL, $nr=5 ) {
    $feed = "http://twitter.com/statuses/public_timeline.rss";
    if($id) $feed = str_replace( "public_timeline", "user_timeline/".$id, $feed );

    $ch = curl_init($feed);
    curl_setopt($ch,CURLOPT_RETURNTRANSFER, true);
    curl_setopt($ch,CURLOPT_HEADER, 0);
    curl_setopt($ch,CURLOPT_USERAGENT,"GREY");
    curl_setopt($ch,CURLOPT_TIMEOUT,10);
    $data = curl_exec($ch);
    if (curl_errno($ch) !== 0 || curl_getinfo($ch, CURLINFO_HTTP_CODE) !== 200) {
        $data === false;
    }
    curl_close($ch);

    $xml = new SimpleXmlElement($data, LIBXML_NOCDATA);
    if(!$xml->error) {
        $i = 0;
        $return = "<ul class='twitter_list'>";
        foreach( $xml->channel->item as $row ) {
            if( $i<$nr ) {
                (isset($id)) ? $title = preg_replace( "/^$id: /",'', $row->title) : $title = $row->title;

                $title = preg_replace('@(https?://([-\w\.]+)+(:\d+)?(/([-\w/_\.]*(\?\S+)?)?)?)@', '<a href="$1">$1</a>', $title);
                $title = preg_replace("/@(\w+)/", '<a href="http://twitter.com/$1">@$1</a>', $title);
                $title = preg_replace("/#(\w+)/", '<a href="http://twitter.com/#search?q=$1">#$1</a>', $title);

                $return .= "
<li>". $title ."</li>
";
            }

            $i++;
        }

        update_option('grey_twitter_timeline', $return);
        return $return . "";
    } else {
        return get_option('grey_twitter_timeline');
    }
}

?>