I find the answer,update qa-page.php, like below:
foreach ($qa_content['navigation'] as $navtype => $navigation)
if (is_array($navigation) && ($navtype!='cat'))
foreach ($navigation as $navprefix => $navlink)
if ((substr($requestlower.'$', 0, strlen($navprefix)) == $navprefix)||(strtolower(@$navlink['url'])==$selfpathhtml))
$qa_content['navigation'][$navtype][$navprefix]['selected']=true;
but then the next bug appears:
