Search Engine Referrer & Keyword PHP Script Problem

I have a slight problem with a php class that is intended to determine the visiting search engine and keywords used then display them on the page. I get the script to properly report the referrer but not the keyword.

Code below and attached.

The Php Class;

<?php
class search_keywords{
      var $referer;
      var $search_engine;
      var $keys;
      var $sep;
      function search_keywords(){
            $this->referer = '';
            $this->sep = '';
            if ($_SERVER['HTTP_REFERER'] OR $_ENV['HTTP_REFERER']){
                  $this->referer = urldecode(($_SERVER['HTTP_REFERER'] ? $_SERVER['HTTP_REFERER'] : $_ENV['HTTP_REFERER']));
                  $this->sep = (eregi('(\?q=|\?qt=|\?p=)', $this->referer)) ? '\?' : '\&';
            }
      }
      function get_keys(){
            if (!empty($this->referer)){
                  if (eregi('www\.google', $this->referer)){
                        // Google
                        preg_match('#{$this->sep}q=(.*?)\&#si', $this->referer, $this->keys);
                        $this->search_engine = 'Google';
                  }else if (eregi('(yahoo\.com|search\.yahoo)', $this->referer)){
                        // Yahoo
                        preg_match('#{$this->sep}p=(.*?)\&#si', $this->referer, $this->keys);
                        $this->search_engine = 'Yahoo';
                  }else if (eregi('search\.msn', $this->referer)){
                        // MSN
                        preg_match('#{$this->sep}q=(.*?)\&#si', $this->referer, $this->keys);
                        $this->search_engine = 'MSN';
                  }else if (eregi('www\.bing', $this->referer)){
                        // Bing
                        preg_match('#{$this->sep}q=(.*?)\&#si', $this->referer, $this->keys);
                        $this->search_engine = 'Bing';
                  }else if (eregi('search\.aol', $this->referer)){
                        // AOL
                        preg_match('#{$this->sep}q=(.*?)\&#si', $this->referer, $this->keys);
                        $this->search_engine = 'AOL';
                  }else if (eregi('www\.alltheweb', $this->referer)){
                        // AllTheWeb
                        preg_match('#{$this->sep}q=(.*?)\&#si', $this->referer, $this->keys);
                        $this->search_engine = 'AllTheWeb';
                  }else if (eregi('(looksmart\.com|search\.looksmart)', $this->referer)){
                        // Looksmart
                        preg_match('#{$this->sep}qt=(.*?)\&#si', $this->referer, $this->keys);
                        $this->search_engine = 'Looksmart';
                  }else if (eregi('(askjeeves\.com|ask\.com)', $this->referer)){
                        // AskJeeves
                        preg_match('#{$this->sep}q=(.*?)\&#si', $this->referer, $this->keys);
                        $this->search_engine = 'AskJeeves';
                  }else{
                        $this->keys = 'Not available';
                        $this->search_engine = 'Unknown';
                  }
                  return array($this->referer,(!is_array($this->keys) ? $this->keys : $this->keys[1]),$this->search_engine);
            }
            return array();
      }
} ?>

My code on the page to report the information;

<?php
require_once('lib/class/searchkeys.class.php');
$keys =& new search_keywords();
$keys = $keys->get_keys();
if (count($keys)){
      print '<p align="center">Directed to this page from <strong>'.$keys[2].'</strong> search engine, within Keywords <strong>'.$keys[1].'</strong></p>';
}else{
      print '<p align="center">nope</p>';
}
?>