jQuery event fire when all boxes are checked

gistfile1.js

I have a table. 1st column is a column for checkboxes and 2nd column is normal data.
When I check a check a single box I get an alert due to the following function which is as expected.

//To catch events when check boxes are checked.
$('input:checkbox').live('change', function() {
  alert("Checked!");
});

But when I check all checkboxes using the command below, I don't get the alert from the function above.

//This checks all the checkboxes
$('input:checkbox').attr('checked', true);

Where am I going wrong?