jQuery checkbox click event is not working

this section of javascript should should trigger when checking a checkbox, nevertheless it never responds. what is wrong with it?

$(function() {
    $('label#defaultStockNonZero').on('click', 'input:checkbox#defaultStockNonZero', function(){
        if ($('input#defaultStockNonZero:checked').length) {

            .. do something ..
        } 
    });
});