Problem with dropdown & jquery

Code:

&lt;?php

class Indicatori extends Controller {



    function Indicatori()

    {

        parent::Controller();

        $this->load->helper(array('form', 'url'));

    }

    

    function index()

    {

        echo '.';

    }

    

    function parametri()

    {

        $this->output->enable_profiler(TRUE);        

        $this->load->model('Parametri','',TRUE);

        $this->load->helper('url');

        $this->load->helper('form');

        $this->load->view('selparametri');        

    }

    function prova()

    {

        $this->load->database();

        

        if (isset($_POST['indicatore1']) && $_POST['indicatore1']!='') 

        {

             $options ='';

            echo     $options.= '<option value="001" class="dynamic">1value1</option>';

            echo     $options.= '<option value="001" class="dynamic">1value2</option>';

            echo     $options.= '<option value="001" class="dynamic">1value3</option>';

     

        }

        if (isset($_POST['indicatore2']) && $_POST['indicatore2']!='') 

        {

             $options ='';

            echo     $options.= '<option value="001" class="dynamic">2value1</option>';

            echo     $options.= '<option value="001" class="dynamic">2value2</option>';

            echo     $options.= '<option value="001" class="dynamic">2value3</option>';

        }

        

    } 

}

/* End of file indicatori.php */ 

/* Location: ./system_osp/application/controllers/indicatori.php */

Code:

&lt;html&gt;

&lt;head&gt;

&lt;title&gt;OSP - Selezione parametri&lt;/title&gt;

[removed][removed]

[removed]

     

function test(step)

{

    var valore = $("#indicatore" + step).val();

    

    $.ajax({

           url: "&lt;?=base_url();?&gt;index.php/indicatori/prova",

           global: false,

           type: "POST",

           async: false,

           dataType: "html",

           data: "indicatore" + step + "="+ valore, //the name of the $_POST variable and its value

           success: function (response) //'response' is the output provided by the controller method prova()

                       {

                       //counts the number of dynamically generated options

                       var dynamic_options = $("*").index( $('.dynamic')[0] );

                    //removes previously dynamically generated options if they exists (not equal to 0)

                       if ( dynamic_options != (-1)) $(".dynamic").remove();

                    $("#indicatore" + (step + 1)).show();

                       $("#indicatore" + (step + 1)).append(response);

                    

                       }

                   

          });

    

    

    return false;

}

[removed]

&lt;/head&gt;

&lt;body&gt;

    <h1>OSP - Selezione parametri</h1>

    

    &lt;?php 



    $attributes = array('class' => 'parametri', 'id' => 'parametri');



    echo form_open('indicatori/parametri', $attributes);

    

    $options = array();



        $query = $this->db->query('SELECT codice, descrizione FROM indicatori');



        foreach ($query->result_array() as $row)

        {

            $options[$row['codice']] = $row['descrizione'];

        }

    $js = 'id="indicatore1" onChange="test(1)"';

    echo form_dropdown('indicatore1', $options,'TRUE',$js);



    $options = array("000" => "Selezionare");

    $js = 'style="display: none" id="indicatore2" onChange="test(2)"';

    echo form_dropdown('indicatore2', $options,'TRUE',$js);

        

    $options = array("000" => "Selezionare");

    $js = 'style="display: none" id="indicatore3" onChange="test(3)"';

    echo form_dropdown('indicatore3', $options,'TRUE',$js);

    

    echo form_close();

        

    ?&gt;

&lt;/body&gt;

&lt;/html&gt;