jQuery sort elements using data id

I have an HTML structure as follows:

<div class="clist">
    <div data-sid=1></div>
    <div data-sid=2></div>
    <div data-sid=2></div>
    <div data-sid=1></div>
    <div data-sid=2></div>
    <div data-sid=2></div>
    <div data-sid=1></div>
</div>

I would like to sort them as:

<div class="clist">
    <div data-sid=1></div>
    <div data-sid=1></div>
    <div data-sid=1></div>
    <div data-sid=2></div>
    <div data-sid=2></div>
    <div data-sid=2></div>
    <div data-sid=2></div>
</div>

I am using the following function:

function sortContacts() {
    var contacts = $('div.clist'), cont = contacts.children('div');

    cont.detach().sort(function(a, b) {
        var astts = $(a).data('sid');
        var bstts = $(b).data('sid')
        return (astts > bstts) ? (astts > bstts) ? 1 : 0 : -1;
    });

    contacts.append(cont);
}

It is not working as expected.

It is working well for the first run but after adding new element or changing the data-sid attributes it no longer works.

Demo: http://jsfiddle.net/f5mC9/1/

Not working?