Can anyone tell me why this code brings up the Advanced Search page *INSTEAD* of the advanced_search_results page?

PHP Code:
</div>' . (($_SESSION['engine']) ? '<div style="text-align:right;"><br /><a href="index.php?main_page=advanced_search_result&product='. $_SESSION['product'] .'&make='. $_SESSION['make'] .'&model='. $_SESSION['model'] .'&exac_model='. $_SESSION['exac_model'] .'&engine='. $_SESSION['engine'] .'"><font style="color:#fff;">View products</font></a></div>': '');