Please help , its not work for me this is my code , i just find the second dropdown menu disabled and not changed any idea ?
 
function index()
    {
        $this->load->library('grocery_CRUD');
        if (!$this->ion_auth->logged_in()) {
            // redirect them to the login page
            redirect('user/login', 'refresh');
        } else {
            $crud = new Grocery_CRUD();
            $crud->set_table('venues');
            $crud->set_subject(' ');
            $crud->unset_delete();
            //$crud->unset_jquery();
            $crud->unset_bootstrap();
            $crud->unset_export();
            $crud->unset_print();
            $crud->unset_read();
            $crud->unset_list();
            $crud->unset_back_to_list();
            $crud->unset_fields('v_started_date', 'v_end_date', 'v_active', 'user_id', 'v_event_counter');
            $crud->unset_edit_fields('v_started_date', 'v_end_date', 'v_active', 'user_id', 'v_event_counter', 'v_accept_agreement');
            $crud->display_as('v_name', __('Venue Name'))
                ->display_as('region_id', __('Region'))
                ->display_as('location_id', __('Location'))
                ->display_as('v_logo', __('Venue Logo'))
                ->display_as('v_address_1', __('Address 1'))
                ->display_as('v_address_2', __('Address 2'))
                ->display_as('v_city', __('City'))
                ->display_as('v_phone_number', __('Phone Number'))
                ->display_as('v_accept_agreement', '');
            // fields type
            $crud->set_field_upload('v_logo', 'assets/uploads/files');
            $crud->set_relation('region_id', 'regions', 'country');
            $crud->set_relation('location_id', 'locations', 'location');
            // dependent dropDown menu
            $this->load->library('gc_dependent_select');
            $fields = array(
                            // first field:
                            'region_id' => array( // first dropdown name //
                             'title' => 'country', //
                             'relate' => null // the first dropdown hasn't a relation
                            ),
                            // second field
                            'location_id' => array( // first dropdown name
                                'table_name' => 'locations',
                                'title' => 'location',
                                'id_field' => 'location_id',
                                'relate' => 'region_id',
                                'data-placeholder' => 'Select Location'
                            ));
            $config = array(
                'main_table' => 'regions',
                'main_table_primary' => 'region_id',
                "url" => base_url() .__CLASS__ . '/' . __FUNCTION__ . '/',
                'ajax_loader' => '',
                'segment_name' => '' // It's an optional parameter. by default "get_items"
            );
            $categories = new gc_dependent_select($crud, $fields, $config);
            // first method:
            //$output = $categories->render();
            // the second method:
            // callback function
            $crud->callback_add_field('v_accept_agreement', array($this, 'add_field_v_accept_agreement'));
            $crud->callback_after_insert(array($this, 'insert_start_date_after_insert'));
            // validation fields
            $crud->required_fields('v_name', 'v_accept_agreement');
            $crud->set_rules('v_accept_agreement', '', 'callback_required_field_v_accept_agreement_msg');
            // elements change text
            $crud->set_lang_string('form_save', __('Subscribe Now'));
            $crud->set_lang_string('insert_success_message',
                ' Your data has been successfully stored into the database.
                <br/>
                 Please wait while you are redirecting to the list page.
                 <script type="text/javascript">
                  window.location = "' . site_url() . '";
                 </script>'
            );
            $js = $categories->get_js();
            $output = $crud->render();
            $output->output .= $js;
            $this->load->vars($output);
            $this->layout->render_page('venue/index');
        }
    }