jQuery not posting all inputs of a form after the .append()

I have a form generated dynamically with the method .append() of jQuery. I can add any number of new input, textbox, cmbbox, etc...

But the problem is that when I do the sumbit of the form, the PHP target does not receive the new input added, but just the vars connected to the input already in the form before the append().

Any ideas?

The javascript:

$("#button").live('click',function add(){
   $("#list").append(
       '<li style="height:20px;">'
    +'<input type="text" class="text" id="prova" name="prova[]" value="prova">'+ 
       '</li>'
   );
});

The Html:

<input type="submit" id="button" value="Add input">
<form name = "form" id="form" action="post.php" method="POST">
   <ul style="width:670px;padding:0px 0px 30px 0px" id="list">
   </ul>
   <input type="submit" id="submit" value="Submit">
</form>

The PHP:

<?php
  print_r($_POST);
?>