By using parent.location.reload(), you are reloading the page on the onClick of the button, before the form is submited.
ussusally to open a lightbox, you just change the Display Property from none to block. To close the lighbox, you change the display property from block to none.
I'm not positive, but that may be what parent.Shadowbox.close(); does, try that with out the parent.location.reload() in front of it.