FormCheck is not actively maintained, AFAIK (it has its own list, too). I would suggest Moo's native Form.Validator: http://mootools.net/docs/more/Forms/Form.Validator
If you don't want to change over right away, if you could put up your sample FormCheck code in a jsFiddle, it's more likely that someone will try to fix it for you, but my 2ยข is that you shouldn't roll out FC right now if you want to, for example, have something that will work with current and future Moo. -- Sandy
