Payment Method Column in Admin Orders Table Grid

Question

I have weird problem, I am trying to show the payment methods in a separate column in admin order grid, the problem is below code is working perfectly in localhost, however in the live server it is not showing. the only thing is filter showing in the top header. here is my code:

protected function _prepareCollection()
{
    $collection = Mage::getResourceModel($this->_getCollectionClass());
    $collection->join(array('payment'=>'sales/order_payment'),'main_table.entity_id=parent_id','method');
    $this->setCollection($collection);
    return Mage_Adminhtml_Block_Widget_Grid::_prepareCollection();
}

......

    $payments = Mage::getSingleton('payment/config')->getActiveMethods();
    $methods = array();
    foreach ($payments as $paymentCode=>$paymentModel){
        $paymentTitle = Mage::getStoreConfig('payment/'.$paymentCode.'/title');
        $methods[$paymentCode] = $paymentTitle;
    }

    $this->addColumn('method', array(
        'header' => Mage::helper('sales')->__('Payment Method'),
        'index' => 'method',
        'filter_index' => 'payment.method',
        'type'  => 'options',
        'width' => '70px',
        'options' => $methods,
    ));