I have two problems when i upgraded a site from 2.4 to 3.1:
problem 1: I'm trying to show xxx fields from parameterFields This doesn't work. The $params field remains empty
problem 2: I'm trying to export the report to csv, however after export I only get the ID's in my csv..

<?php

class CustomSideReport_TipcompetitieReport extends SS_Report{
  function title() {
    // the name of our report
    return "Tipcompetitie";
  } 
  
  function sourceRecords($params) {
    
    //$Pages = DataObject::get("TipcompetitieZend", null, "Kortebaan DESC", null, $limit);  
    $limit = isset($params['ResultsLimit']) ? $params['ResultsLimit'] : '';
    $Pages = TipcompetitieZend::get()->sort("Kortebaan DESC")->limit($limit);//, null, $limit);         
    return $Pages;
  } 
  
  function columns() 
  {
    $fields = array(
        'Naam' => array(
            'title' => 'Naam'
        ),
        'Woonplaats' => array(
            'title' => 'Woonplaats'
        ),
        'Kortebaan' => array(
            'title' => 'Kortebaan'
        ),
        'Emailadres' => array(
            'title' => 'Baan'
        ),
        'nr1' => array(
            'title' => 'Nummer 1'
        ),
        'nr2' => array(
            'title' => 'Nummer 2'
        ),
        'nr3' => array(
            'title' => 'Nummer 3'
        ),
        'nr4' => array(
            'title' => 'Nummer 4'
        ),
        
        'Created' => array(
            'title' => 'Invoerdatum',
            'casting' => 'SS_Datetime'
        )
        
    );
    return $fields;
  }

  public function parameterFields() 
  {
    $params = new FieldList();
     
    //Result Limit
    $ResultLimitOptions = array(
        50 => '50 Aanmeldingen',
        100 => '100 Aanmeldingen',
        200 => '200 Aanmeldingen',
        500 => '500 Aanmeldingen',
        Null => 'Alle aanmeldingen'
    );
     
    $params->push(new DropdownField(
        "ResultsLimit", 
        "Aantal aanmeldingen weergeven",
        $ResultLimitOptions/*,
        10*/
    ));
             
    return $params;
  }   
}
?>