Trying to make average in calc element

[tutux]

Hi

I'm trying to run a calc average displayed on each rows of a list with Ratings fabrik table :

i did it... but... it doesn't work..

$rowidrow = '{rowid}';
$app = JFactory::getApplication();
$rowId = $app->input->getInt( 'row_id', 0 );
$db =& JFactory::getDBO();
$db->setQuery('select avg(rating) from mytable_fabrik_ratings where id_row = '$rowidrow'');
return $db->loadResult();

Thanks !