I just upgraded to 13 (I renamed the old cforms folder and installed the newest file from this website in the Plug-ins interface) and my forms are still intact, but when I tested it, everything worked except my Radio Buttons.. It is supposed to return Yes or No, and it is a required field.  When it emails me back it shows the Field Name on the left but nothing in the output.

I created a completely new form with only a radio box, and it did not send the value of the selection either.

thanks for your help!

EDIT: I also tried adding a form with radio buttons on a different install of WP I manage, fresh install of the plugin and it is not registering the response.

If it helps, here's how the field name looksk after I edit the settings (I've tried it with and without the optional value):

Do you already own the program?#No#Yes

yep, you're right a bug sneaked in, I'll have an update out asap.

v13.1 is out now, fixing the radio button issue.