Hi Penny,

In your form, did you make the "Miles Driven" field read-only? If so then that could be the cause of your issue. If that is the case, then what you would need to do is to use Javascript to make that field read-only. Here's a generic example that works for me.

Form:

Javascript:

$(document).ready(function () {
  $('.dMiles input').attr('readonly','True');
  $('.bMiles input').on("change", function () {
    $('.dMiles input').val($('.eMiles input').val()-$('.bMiles input').val());
  });
  $('.eMiles input').on("change", function () {
    $('.dMiles input').val($('.eMiles input').val()-$('.bMiles input').val());
  });
});

The beginning mileage field uses the CSS class, bMiles. The ending mileage field uses the CSS class, eMiles. The miles driven field uses the CSS class, dMiles.

Report:

If you're still having an issue, can you let us know what version of Forms you're using and also what Javascript you're using?

Regards