Trying to Add Required Checks in Boxes

Hello, I'm trying to add an acknowledgement, where I want the user to check four boxes, acknowledging four items.  I set the response to four minimum/maximum but for some reason when I preview the form, that section is not appearing.  Is there a better way to do this?

Thanks!

Kari

I checked your form http://www.jotform.us/form/63124001164136 and the mentioned field, but I didn't notice anything wrong:

Please let us know if you need any further assistance.

Thank you!