php - Grid column does not work on Server -

i want add column in order grid value come block. code used in grid.php given below :

    $this->addcolumn('sum_total', array(     'header' => mage::helper('sales')->__('g.t.used'),     'column_css_class' => 'a-right',     'type'  => 'currency',     'currency' => 'base_currency_code',     'renderer' => 'marketplace_mpshippingmanager_block_adminhtml_sumtotal'     )); 

here code used in block :

class marketplace_mpshippingmanager_block_adminhtml_sumtotal extends mage_adminhtml_block_widget_grid_column_renderer_abstract {   public function input_render(varien_object $row)   {     //echo '$'.(float)($row['base_subtotal']-$row['base_grand_total']);      printf("$%.2f", ($row['base_subtotal'] - $row['base_grand_total']));   }  } 

it work on localhost make problem on server. why?

if 1 more appreciable.

is localhost windows? server linux? can't ran earlier in week turned out windows case insensitive , linux case sensitive. varien autoloader parses classnames , strings throwing in '\' didn't want them , magento not find files.

i not know if helps but, similar problem figured put in 2 cents. here thread problem explained smarter person. https://stackoverflow.com/questions/30085012/magento-mass-action-grid-does-not-update