Checkboxes help needed

Hi,

Everything is working perfectly apart from a check box..

I want it to say something like:
“please untick this box if you wish to not be be contacted in the future”

So i put the code like please untick this box[checkbox opt_out "if"]you wish to not be be contacted in the future.

This displays the box in the right location, though on the email form I add the code of: Opt out? [checkbox]

Sadly if i tick the box or nor, all i get is [checkbox]

Can anyone help me, I have a feeling i am doing something stupid…

Thanks,
Cundall

http://wordpress.org/plugins/contact-form-7/