Disable button if all checkboxes are unchecked and enable it if at least one is checked

Try this:

var checkBoxes = $('tbody .myCheckBox');
checkBoxes.change(function () {
    $('#confirmButton').prop('disabled', checkBoxes.filter(':checked').length < 1);
});
checkBoxes.change(); // or add disabled="true" in the HTML

Demo

Explanation, to what I changed:

• Cached the checkbox element list/array to make it a bit faster: var checkBoxes = $('tbody .myCheckBox');
• removed the if/else statement and used prop() to change between disable= true/false.
• filtered the cached variable/array checkBoxes using filter() so it will only keep the checkboxes that are checked/selected.
• inside the second parameter of prop added a condition that will give true when there is more than one checked checkbox, or false if the condition is not met.

Add an event handler that fires when a checkbox is changed, and see if there are any checked boxes, and set the disabled property appropriately :

var boxes = $('.myCheckBox');

boxes.on('change', function() {
    $('#confirmButton').prop('disabled', !boxes.filter(':checked').length);
}).trigger('change');

FIDDLE

Try this:

$('tbody').click(function () {

   if ($('.myCheckBox:checked').length >= 1) { 
           $('#confirmButton').prop("disabled", true);
       }
   else {
            $('#confirmButton').prop("disabled", false);
   } 

 });

DEMO