Shipping costs not calculating correctly

[cebegebees]

HI,

We have 2 shipping rates, a flat rate of €5 per order for most products but there are some smaller items that go out in the regular post which we have charge €1 per order.

This all works fine regardless of how many products you order, the same flat rate is charged.

However, when you order a small product and a large product you get charged €6 shipping. How can I make it that it is just the €5 as they would all go in the one box?

I am using version 1.6.1.19 and the default bootstrap theme.

Thanks