Problem with session

Question

I am working in Drupal and Magento Integration

Whenever i try to get session data using this code

require_once $_SERVER['DOCUMENT_ROOT'] . "/mage1/app/Mage.php";
  umask(0);
  Mage::app("default");

  $session = Mage::getSingleton("customer/session");

  if ($session->isLoggedIn()) {
    $block['content'] .= $session->getCustomer()->getName();
    #var_dump($session->getData());
  }
  else {
    $block['content'] = t('User not logged in');
  }

it fails to fetch the data.

But when i run this from independent php code it works fine.

But magento's catalog objects are running perfectly inside Drupal

What could be the problem. Any suggestions

Am using D7

EDIT

require_once $_SERVER['DOCUMENT_ROOT'] . "/mage1/app/Mage.php";
      umask(0);
      Mage::app();
      Mage::app()->getTranslator()->init('frontend');
      Mage::getSingleton('core/session', array('name' => 'frontend'));

      // switch off error reporting
      error_reporting(E_ALL & ~ E_NOTICE);

      // Brands category => ID = 101
      $brand = Mage::getModel('catalog/category')->load('4');
      $brands = $brand->getChildrenCategories();

      foreach ($brands as $node) {
        $items[] = array(
            'data' => t($node['name'])
        );
      }

      $block['content'] .= theme('item_list', array(
          'items' => $items
              ));

This is the code i use to get the catalog products from magento and display in drupal I don't use any package for that.This is working perfectly.