When using a checkbox on a form, the label ID, and the input ID do not match, therefore the user cannot click on the label to check/uncheck the box. This is more of an issue on mobile devices, but is also inconvenient in other browsers, since clickable labels are common.
A sample is at: http://www.lycomfg.com/contact/contact-information/ and can be seen in the checkobx labeled "Request a Demo" located right above the submit button.
In this case, the checkbox input has an ID of "input_7.1", and the label has a FOR attribute of "choice_7_1"
