revisa el error en la consulta a ver que pasa
Código PHP:
$aux = mysql_query (" SELECT B.products_id, B.image_path ".
" FROM banners B, banners_to_categories BC ".
" WHERE B.banners_id = BC.banners_id ".
" AND BC.categories_id = $idcategoria ", $tooqDB
) or die ("Error: " . mysql_error());