I downloaded the above Module Kit from this site and used it as a bases for a contact us form.

I really like the look of the popup Validation error messages on this which is why I used it.  I was able to add new text fields and dropdown lists and to get the validator to work.

On the form I added a checkbox called Agreement.  I want to set this so that the user has to check this box in order to submit the form.  I followed the similar pattern as the text fields and gave the check box the class="validate[required]".  But now when I click the Submit button not only doesn't the validator work on the checkbox it also doesn't run for any of the text fields.

Any ideas?