Got an issue when trying to filter a joined column in my new grid items, redirecting me to dashboard. This only affects the join column, I can filter with no problem the other fields. The code:

public function __prepareCollection() {    $  collection = Mage::getModel('catalog/product)->getCollection()         ->addAttributeToSelect(array(name, supplier));    $  collection->joinLeft(array('sell' => 'table_sell','sell.product_id = e.entity_id',                 array('grid_field' => 'count(case when sell.status > 0 then sell.quantity else 0 end'))               ->group('entity_id');    $  this->setCollection($  collection);    return parent::_prepareCollection(); }  protected function _prepareColumns() {    $  this->addColumn('grid_field', array(    'header' => Mage::helper('custom')->__('Grid field'),    'type' =>  'number',    'width' => '50px',    'index' => 'grid_field' )); }  public function getGridUrl() {    return $  this->getUrl('*/*/sellgrid', array('_current' => true)); } 

I must say that the action controller responsible for retuning the grid is:

public function sellGridAction(){     $  this->loadLayout();     $  this->renderLayout(); } 

Any ideas? I also tried:

$  collection->addFilterToMap('grid_column', 'sell.count(case when sell.status > 0 then sell.quantity else 0 end'); 

but no result.