Magento 1.5.0.1 Bug: Call to a member function loadPriceData() on a non-object

Open app\code\core\Mage\Catalog\Model\Product\Attribute\Backend\Tierprice.php

Comment out lines from 202 to 219

Error:Fatal error: Call to a member function loadPriceData() on a non-object in E:\wamp\www\magento\app\code\core\Mage\Catalog\Model\Product\Attribute\Backend\Tierprice.php on line 202

/* $data = $this->_getResource()->loadPriceData($object->getId(), $websiteId);
foreach ($data as $k => $v) {
$data[$k]['website_price'] = $v['price'];
if ($v['all_groups']) {
$data[$k]['cust_group'] = Mage_Customer_Model_Group::CUST_GROUP_ALL;
}
}

if (!$object->getData('_edit_mode') && $websiteId) {
$rates = $this->_getWebsiteRates();

$full = $data;
$data = array();
foreach ($full as $v) {
$key = join('-', array($v['cust_group'], $v['price_qty']));
if ($v['website_id'] == $websiteId) {
$data[$key] = $v;
$data[$key]['website_price'] = $v['price'];
} else if ($v['website_id'] == 0 && !isset($data[$key])) {
$data[$key] = $v;
$data[$key]['website_id'] = $websiteId;
if ($object->getPriceModel()->isTierPriceFixed()) {
$data[$key]['price'] = $v['price'] * $rates[$websiteId]['rate'];
$data[$key]['website_price'] = $v['price'] * $rates[$websiteId]['rate'];
}
}
}
}

$object->setData($this->getAttribute()->getName(), $data);
$object->setOrigData($this->getAttribute()->getName(), $data);

$valueChangedKey = $this->getAttribute()->getName() . '_changed';
$object->setOrigData($valueChangedKey, 0);
$object->setData($valueChangedKey, 0); */