JS conflict for datepicker?

...

$(document).ready(function(){
    $('input#input_1_6').datepicker({beforeShowDay: function(date){
        return [(date.getDay() > 1), ''];
    }});
});

...but I've since changed the theme I was using and it's no longer blocking out those days. I suspect it could be a conflict with some other JS but can't work out it could be. Could someone help to point me in the right direction?

Here is a link to the page with the form: http://alturl.com/jiptg

Thanks!