Unchecked Checkbox (Yes/No) with Choice

Hi everybody,

I'm trying to unmark the checkbox when I change the choice using the following function:

function vChanged(){
NWF$('input[type=checkbox]').each(function(){
NWF$(this).prop('checked',false);

});
}

NWF$('#' +MyVariable).click(function() {vChanged(); }); //I use the variable "MyVariable" in Choice 

But, when I change the choice option visibly the checkbox is unchecked but the value in the calulated is equal to true, as I can besides unchecking the value to false, this is impacting on the rules of the form that uses the value of the checkbox