I am working on a form with a subform which can have additional instances generated by means of a button. This subform contains several text fields as well as a set of checkboxes. When multiple instances are present, the text fields in each behave as separate fields -- you can fill in different text in each -- but a given checkbox in each instance behaves as all the same checkbox, i.e. if you check it in one instance, it checks in every instance. Why is it being like this and how do I make it stop?