I use Adobe Pro DC. I created a form with several questions and each question has a drop down list of answers. Each answer has its own value. I have a total score botton to sum up all the vaules from the answers.
I can sum up the values from my end before I email the form to the client to fill and sign, however after I emailed the form to the client, the value remains 0 on his end. In return, I recevied a form with a 0 score.
Maybe they didn't press the button... You should use a field with a calculation script or formula to achieve this, instead of a button. However, you have to keep in mind that there are a lot of bad PDF viewers out there, where such calculations are not likely to work. So you need to instruct your users to stick to Adobe Reader, or you need to perform those calculations yourself, and not rely on them working on the user's machine.