Passing multiple callback in Code Igniter form validation rules

I want to pass multiple callbacks in codeigniter form validation rules.... but only one of the callbacks work

I am using this syntax in my contoller

$this->form_validation->set_rules(           
                array(
                    'field' => 'field_name',
                    'label' => 'Field Name',
                    'rules' => 'callback_fieldcallback_1|callback_fieldcallback_2[param]',
                    'errors' => array(
                        'fieldcallback_1' => 'Error message for rule 1.',
                        'fieldcallback_2' => 'Error message for rule 2.',
                        )
                    ),
                );

and the callback functions are....

function fieldcallback_1 (){
      if(condition == TRUE){
              return TRUE;
      } else {
              return FALSE;
      }

}

function fieldcallback_2 ($param){
      if(condition == TRUE){
              return TRUE;
      } else {
              return FALSE;
      }

}

Someone please help me out with this problem.... any other solutions regarding passing multiple callbacks in form validation rules are also appreciated...

All validation routines must have at least one argument which is the value of the field to be validated. So, a callback that has no extra arguments should be defined like this.

function fieldcallback_1($str){
      return ($str === "someValue");
}

A callback that requires two arguments is defined like this

function fieldcallback_2 ($str, $param){
    //are they the same value?
    if($str === $param){
        return TRUE;
     } else {
         $this->form_validation->set_message('fieldcallback_2', 'Error message for rule 2.');
         //Note: `set_message()` rule name (first argument) should not include the prefix "callback_"
         return FALSE;
}