Calculation does not work properly

I am making a form to calculate a certain cost. I have made fields where the user can fill in a certain distance in kilometers. There is one calculation that adds all of those fields up (which works normally). Then there is another calculation that multiplies the total distance with a certain number (in this case 0.4237). But for some reason this calculation doesn't work properly. It's as if it's delayed. When I give in a number in the distance field, it adds up in the TOTAL field. But it doesn't multiply in the other field. ONLY when i give in a second distance it starts multiplying, but only the previous number. This happens everytime: you give in the 3rd number it multiplies the previous 2. Very confusing. For reference I will put the PDF form in this post.

PS I have no experience in Java.