分页显示超过设定限制

Question

我对Magento很新，我在自定义集合上遇到分页问题。我将页面限制设置为5，但是，所有六个结果都显示（请参阅screenshot）。

public function __construct()
{
    parent::__construct();

    //............

    $oItems = new Varien_Data_Collection();

    foreach ($collection as $col) {
        $order = Mage::getModel("sales/order")->load($col->getId());
        $items = $order->getAllVisibleItems();
        //Mage::log(count($items));
        foreach($items as $item) {
            $varienObject = new Varien_Object();
            $varienObject->setName($item->getName());
            $varienObject->setProductId($item->getProductId());
            $varienObject->setProductOptions($item->getProductOptions());
            $oItems->addItem($varienObject);
        }
    }

    $this->setCollection($oItems);
}

protected function _prepareLayout()
{
    parent::_prepareLayout();

    $pager = $this->getLayout()->createBlock('page/html_pager', 'custom.pager');
    $pager->setAvailableLimit(array(5=>5,10=>10,25=>25,'All'=>'All'));
    $pager->setCollection($this->getCollection());
    $this->setChild('pager', $pager);
    $this->getCollection()->load();
    return $this;
}

我知道我必须亲近，但我显然错过了一些东西。