You have created a shipping table with several rows containing rules and their respective shipping costs. But, when you test these prices at checkout, the shipping cost is always free no matter how many items are in the cart. The most common cause for this is an empty row in the table. An empty row is still a valid row. The empty Conditions column means there are no requirements to qualify for this row in the table. The empty Cost column is the equivalent of $0 shipping. So an empty row anywhere in your table would nullify any conditions set before it.
Simply remove any empty rows from your table and things will continue running smoothly again.