Rule Reference for greater_than/less_than value checking with using callback

Code:
public $rules = array(

                       'name' => array(

                                        'field'  => 'name',

                                        'label'  => 'Course',

                                        'rules'  => 'trim|required',

                                        'errors' => array(

                    

                     'one_time_payment' => array(

                                        'field'  => 'one_time_payment',

                                        'label'  => 'Onetime Payment',

                                        'rules'  => 'trim|required|integer',

                                        'errors' => array(

                                                                          'required' =>"Please enter Onetime Pay Amount",

                                                                      ),

                     ),

                    'installment_payment' => array(

                                        'field'  => 'installment_payment',

                                        'label'  => 'Installment Payment',

                                        'rules'  => 'trim|required|greater_than[one_time_payment').']');,

                                        'errors' => array(

                                              'required' =>"Please enter Installment Amount",

                                             'greater_than'=>'Plase enter some greater value than Onetime payment'

                                                                      ),

                      ),







    );