I sent that last reply too early. Code on line 24 is
$query_rsDetail = sprintf("SELECT stock - (SELECT coalesce(sum(DetailQuantity),0) as soldStock from orders INNER JOIN orderdetails ON OrderID = DetailOrderID WHERE DetailProductID = ProductID AND OrderDate > stock_update) as newStock FROM products WHERE productID = %s", GetSQLValueString($colname_rsDetail, "int"));
This was added when I was entering an inventory control section to the site and was done in conjunction with one of the Webassist tech guys. As I needed help to implement it, I don't know how to work out what's going wrong.