Inside WordPress, when the button is pressed the calculations are performed and the fields are populated correctly, but then all the form fields go blank and the URL changes from
So it somehow seems to be redirecting to the same page but with both the entered and calculated form field values encoded as parameters in the URL.
It works find outside of wordpress. I've tried both putting the form in the page content and in the template. It's running on Apache and I'm using pretty permalinks.
Any ideas? Any help or pointers in the right direction would be greatly appreciated.