Il segunte codice mi da errore relativamente alla concatenazione condizionale in grassetto. come mai?
codice:
<?php

   require 'config.inc'; // simple general setting ;-)
   require 'language.en.inc'; // language settings
   require 'display.inc'; // it's the function that print the markup

   $title = "<span id='titletop'>$wikititle - </span><span id='tit_nav'>$newcat</span>";

   if(isset($_COOKIE['username'])){
   $node = "<h4>Welcome " . $_COOKIE['username'] . "!</h4>\n";}
   else {$node = "<h4>you are not logged in!</h4>\n";}


if(isset($_POST['submit'])){
   node .= "hai inviato il modulo";
   }


   $node .= "[/list]\n<form action='addcat.php' method='post'>\nnew category:
<input type='text' name='newcatname' class='input' />\n<input type='submit' name='submit' value='add category' id='send' />\n</form>";

      // navigation bar
      require 'navigation.inc';

      // here is where everything will be printed by using the function "display" defined in display.inc
      display($title, $node, $navigation, $templatenode);

?>