debugging a library server side

Code:
function login() {

    

        $data['h1'] = 'cms login';

        $data['nomenu'] = 'y'; // hide menu as this is the login page



        

        // ---------------------------

        //       SET VALIDATION

        // ---------------------------

        $this->load->library('validation');

        

        // check incoming variables

        $rules['login_username'] = "required|min_length[4]|max_length[32]|alpha_dash";

        $rules['login_password'] = "required|min_length[4]|max_length[32]|alpha_dash";

        

        $this->validation->set_rules($rules);

        

        $fields['login_username'] = 'Username';

        $fields['login_password'] = 'Password';

        

        $this->validation->set_fields($fields);

        

        $this->validation->set_error_delimiters('<p id="error">','</p>');

        

        // ---------------------------

        //  RUN VALIDATION + SUBMIT DATA

        // ---------------------------

        

        if ($this->validation->run() == false) {

            // form fails to validate

            $data['status'] = "<p class=\"popfirst\">Please login in to the content management system below.</p>";

            $data['login'] = $this->load->view('cms/loginform','',true);

            $this->load->view('cms/cms_view',$data);

            

        } else {

            // form validates ok

            

            if($this->simplelogin->login($this->input->post('login_username'), $this->input->post('login_password'))) {

                // user logged in ok

                redirect('cms');

            

            } else {

                // failed to login

                redirect('cms/login');

            

            }

        }    

        

    

    } //ends login