[SOLVED] Required checkbox

I require users to tick a checkbox before submitting the form, but even though I’ve set it to required it still submits with it being clear.

I have termsandconditions:required in the validation section (and other validations work fine).

And then I have:

<input id="termsandconditions" type="checkbox" name="termsandconditions" [[!+fi.termsandconditions:FormItIsChecked=`Yes`]] />

Any thoughts?

Thanks in advance

Sorry, I found the help I needed in the RTFM at:
http://rtfm.modx.com/display/ADDON/FormIt.Handling+Selects%2C+Checkboxes+and+Radios

Despite being offered a delete button, I can’t delete this topic - so sorry about that.