How to feature radio buttons in email additional headers? (Contact Form 7)

Hi,

I am having problems getting the email to include the answer selected using the radio buttons.

See: http://www.3d-mad.com/feedback-form

The code i’m using for this part of the form is as follows:

<p>Feedback Topic (required)
[radio radio-319 “Site Feedback” “Category Suggestion” “Feature Request” “Site Bug” “Other”] </p>

The code i’m using in the additional headers of the email is:

[radio-319]

Any ideas anybody what is wrong as the email only shows the message?

Many thanks,

Tom