[PROBLEME] boucle et preg_replace

$str = '
<CW_MENUS>
	<div style="border: 1px solid #3b3b3b; margin-top: 20px; width: 100px;">
		<a href="#MENU_LIEN" title="#MENU_TITLE">#MENU_NOM</a>
	</div>
</CW_MENUS>
';

$chaine = preg_replace('#<CW_MENUS>(.+)</CW_MENUS>#sU',menu('$1'),$str);	
echo $chaine;

function menu($str){
	$retour = "";
	
	$sql = "SELECT * FROM cw_menus WHERE visible='1' ORDER BY ordre ASC";
	$req = mysql_query($sql);
	
	while ($data = mysql_fetch_assoc($req)){
		$temp = str_replace('#MENU_NOM',$data['nom'],$str);
		$temp = str_replace('#MENU_LIEN','http://www.aaaa.fr/'.$data['page_id'].'.php',$temp);
		$temp = str_replace('#MENU_TITLE',$data['title'],$temp);
		$retour .= $temp;
	}
	
	return $retour;
}