I've been able to filter custom added column like 'seller name ' its get from seller id of product.
other filters are working.
$this->addColumn('seller_id', array(
'header' => Mage::helper('marketplace')->__('Seller Names'),
'index' => 'seller_id',
'filter' => true,
'sortable' => true,
// 'renderer' => 'marketplace/adminhtml_productrequest_renderer_sellername'
));
when I try to use the column to search I get an error like this.
exception 'Mage_Core_Exception' with message 'Invalid block type: 1' in C:\wamp\www\magento\app\Mage.php:595 Stack trace: C:\wamp\www\magento\app\code\core\Mage\Core\Model\Layout.php(495): Mage::throwException('Invalid block t...') 1 C:\wamp\www\magento\app\code\core\Mage\Core\Model\Layout.php(437): Mage_Core_Model_Layout->_getBlockInstance(true, Array) 2 C:\wamp\www\magento\app\code\core\Mage\Adminhtml\Block\Widget\Grid\Column.php(369): Mage_Core_Model_Layout->createBlock(true) 3 C:\wamp\www\magento\app\code\core\Mage\Adminhtml\Block\Widget\Grid\Column.php(51): Mage_Adminhtml_Block_Widget_Grid_Column->getFilter() 4 C:\wamp\www\magento\app\code\core\Mage\Adminhtml\Block\Widget\Grid.php(314): Mage_Adminhtml_Block_Widget_Grid_Column->setGrid(Object(Mage_Adminhtml_Block_Sales_Order_Create_Search_Grid)) 5 C:\wamp\www\magento\app\code\local\Mage\Adminhtml\Block\Sales\Order\Create\Search\Grid.php(157): Mage_Adminhtml_Block_Widget_Grid->addColumn('seller_id', Array) 6 C:\wamp\www\magento\app\code\core\Mage\Adminhtml\Block\Widget\Grid.php(624):