<?php
class Buildnext_Producteditrequest_Block_Adminhtml_Producteditrequest_Grid
      extends Mage_Adminhtml_Block_Widget_Grid
{
    public function __construct()
    {
        parent::__construct();
        $this->setId('producteditrequestGrid');
        // This is the primary key of the database
        $this->setDefaultSort('pdt_edit_id');
        $this->setDefaultDir('ASC');
        $this->setSaveParametersInSession(true);
    }

    protected function _prepareCollection()
    {
        $collection = Mage::getModel('producteditrequest/producteditrequest')
        ->getCollection()-> addCustomerNameToSelect();


        //echo $collection->getSelect();
        $this->setCollection($collection);
        return parent::_prepareCollection();
    }

    protected function _prepareColumns()
    {
        $this->addColumn('pdt_edit_id', array(
                'header'    => Mage::helper('producteditrequest')->__('ID'),
                'align'     =>'right',
                'width'     => '50px',
                'index'     => 'pdt_edit_id',
        ));

        $this->addColumn('product_code', array(
                'header'    => Mage::helper('producteditrequest')->__('Product Code'),
                'align'     =>'right',
                'width'     => '50px',
                'index'     => 'product_code',
        ));

        $this->addColumn('fullname', array(
            'header' => Mage::helper('producteditrequest')->__('Seller'),
            'align' =>'left',
            'index' => 'seller_id',
            'format' => '$fullname'
        ));

        $this->addColumn('action',
                array(
                        'header'    => Mage::helper('producteditrequest')->__('Action'),
                        'width'     => '50px',
                        'type'      => 'action',
                        'getter'     => 'getId',
                        'actions'   => array(
                                array(
                                        'caption' => Mage::helper('producteditrequest')->__('View'),
                                        'url'     => array(
                                                'base'=>'*/*/edit',
                                        ),
                                        'field'   => 'pdt_edit_id'
                                )
                        ),
                        'filter'    => false,
                        'sortable'  => false,
                        'index'     => 'pdt_edit_id',
                ));

        return parent::_prepareColumns();
    }

    public function getRowUrl($row)
    {
        return $this->getUrl('*/*/edit', array('id' => $row->getId()));
    }
}

Warning: simplexml_load_string(): Entity: line 1: parser error : Start tag expected, '<' not found  in /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Core/Model/Layout/Update.php on line 450

#0 [internal function]: mageCoreErrorHandler(2, 'simplexml_load_...', '/opt/lampp/htdo...', 450, Array)
#1 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Core/Model/Layout/Update.php(450): simplexml_load_string('/**n * Buildnex...', 'Mage_Core_Model...')
#2 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Core/Model/Layout/Update.php(275): Mage_Core_Model_Layout_Update->getFileLayoutUpdatesXml('frontend', 'buildnext', 'brick', '1')
#3 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Core/Model/Layout/Update.php(347): Mage_Core_Model_Layout_Update->fetchFileLayoutUpdates()
#4 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Core/Model/Layout/Update.php(246): Mage_Core_Model_Layout_Update->fetchPackageLayoutUpdates('default')
#5 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Core/Model/Layout/Update.php(224): Mage_Core_Model_Layout_Update->merge('default')
#6 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Core/Controller/Varien/Action.php(306): Mage_Core_Model_Layout_Update->load()
#7 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Cms/Helper/Page.php(109): Mage_Core_Controller_Varien_Action->loadLayoutUpdates()
#8 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Cms/Helper/Page.php(52): Mage_Cms_Helper_Page->_renderPage(Object(Mage_Cms_IndexController), 'no-route')
#9 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Cms/controllers/IndexController.php(75): Mage_Cms_Helper_Page->renderPage(Object(Mage_Cms_IndexController), 'no-route')
#10 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Cms_IndexController->noRouteAction()
#11 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action->dispatch('noRoute')
#12 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#13 /opt/lampp/htdocs/buildnext/marketplace/magento/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
#14 /opt/lampp/htdocs/buildnext/marketplace/magento/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#15 /opt/lampp/htdocs/buildnext/marketplace/magento/index.php(87): Mage::run('', 'store')
#16 {main}