jquery autocomplete插件与json无法完美配合

Question

i write a code for autocomplete a textbox using jquery autocomplete plugin..... but it cann't working properly

here is html

    <input type="submit" value="Search" />
    <input class="searchBox" id="isearch" name="isearch" value="" type="text" />
    <input type="hidden" name="hsearch" id="hsearch" />

and javascript

  $(document).ready(function(){
  $("#isearch").autocomplete(
     "search.php", 

      {
            select: function(event, ui) {
        event.preventDefault();
        $("#isearch").val(ui.item.label);
        $("#hsearch").val(ui.item.value);
        return false;
    },
    focus: function(event, ui) {
        event.preventDefault();
        $("#isearch").val(ui.item.label);
        return false;
    }
});
    });

the PHP code is

    <?php
       include 'config.php';

       $q=$_GET['q']; 
       $my_data=mysql_real_escape_string($q);
       $sql="SELECT emp_id,name FROM f_name WHERE name LIKE '%$my_data%' ORDER BY name";
       $result = mysql_query($sql) or die(mysql_error());
       $results = array();

while($row=mysql_fetch_array($result))
{
    $results[] = array('value' => $row['emp_id'],'label' => $row['name']);
}
echo json_encode($results);

    ?>

and json value that return in textbox is

   [
     {"value":"2","label":"AAA ZZZ"},
     {"value":"3","label":"Roger Fedrer"},
     {"value":"1","label":"Php Admin"}
   ]

i want that textbox only show "label" and "value" should store in hidden-field