Required checkbox on Weblead form

[whitetoo]

Hi gurus!

I am trying to make a checkbox a "required" field on my form.

My checkbox input:

<input name="consent_checkbox" id="consent_checkbox" type="checkbox" />

My required input:

<input id="req_id" name="req_id" value="first_name;last_name;account_name;phone_work;sic_code_dropdown_c;primary_address_postalcode;consent_checkbox;" type="hidden" />

All other fields are successfully checked and the javascript notice pops up to say some fields need to be filled in. However I can submit the form whether I check the consent checkbox or not.

Any ideas what I have missed?