free shipping and does not require shipping products

If either a product with free shipping or a product that doesn't require shipping is added to the basket, the behaviour is as expected, no shipping is charged, however if both are placed in the basket,
ie. one product that has free shipping and one product that doesn't require shipping,
a shipping fee is applied here but shouldn't be

fixed it in method in Shipping Manager:
IsFreeShipping(ShoppingCart cart, Customer customer)

foreach (var sc in cart)
                if (!sc.IsFreeShipping && sc.IsShipEnabled)
                {
                    allItemsAreFreeShipping = false;
                    break;
                }

You're absolutely right. Thanks for info