Menu help

[system]

Hi, I’m trying to build a dynamic website/cms and am having problems with the menu. I have a main menu and a sub-menu (a nested

). The nested list displays when the parent
• element is clicked on, but it dissapears when one of the items in the nested list is clicked on and this looks really bad. I would really appreciate any help - I’ve tried everything! Here is the function:

  [php]function public_navigation($sel_subject, $sel_page, $public = true) {	
  	$output = "<ul class=\"subjects\">";
  	$subject_set = get_all_subjects($public);
  	while ($subject = mysql_fetch_array($subject_set)) {
  		$output .= "<li";
  		if ($subject["id"] == $sel_subject['id']) { $output .= " class=\"selectedsubjects\""; }
  		$output .= "><a href=\"index.php?subj=" . urlencode($subject["id"]) . 
  			"\">{$subject["menu_name"]}</a></li>";
  		if ($subject["id"] == $sel_subject['id']) {	
  			$page_set = get_pages_for_subject($subject["id"], $public);
  			$output .= "<ul class=\"pages\">";
  			
  			while ($page = mysql_fetch_array($page_set)) {
  				$output .= "<li";
  				if ($page["id"] == $sel_page['id']) { $output .= " class=\"selected\""; }
  				$output .= "><a href=\"index.php?page=" . urlencode($page["id"]) .
  					"\">{$page["menu_name"]}</a></li>";
  			}
  			$output .= "</ul>";
  		}
  	}
  	$output .= "</ul>";
  	return $output;
  }[/php]