Hi, I also tried too long, but now I got mine working with checkboxes, which should be similar to radio's.
Put in the form a derive filed like this:
<input type="hidden" name="derive_fields" value="new_checkbox
'%; (keep clear)
(delete the (keep clear)
in the form, it must be empty)
the checkbox in the good_url or here in the email_template must have the name "new_checkbox", the same checkbox in the original form must have the name "old checkbox".
now for the email_template or good_url, instead of typing in $old_checkbox you put in the following line (here checkbox), where you want the box (or radio's):
<input type="checkbox" name="news" value="ON" $new_checkbox
result: because of the derive_field, the $new_checkbox
is replaced by checked oder left empty, what means that you get a checked or not checked checkbox.
not mx best english, but I hope I could help you. First time I wrote in a forum.