Prepare form calculations delayed.

Hi, I've set calculations to happen on the page however it seems the box doesn't perform calculations until I type something in another box. Hard to explain but seeht e images for a better understanding. As you see in example 1 & 2, I completed the calculation in example 1 however no subtotal triggered. As soon as I type in any box "Example 2" as you see I typed in a box below and all of a sudden the calculations populate for what was the first line...can anyone help?