jquery mobile pop up

jquery mobile pop up

i read this:
http://api.jquerymobile.com/1.3/popup/

and i set the following:
html:
 
<div id="both" data-role="popup" data-theme="e" data-overlay-theme="a" class="ui-content">
...Popup contents...
</div>

js:
$('#both').popup('open');
$('#both').popup({
tolerance: "0,0"
});

but is not working...
so please: what's the problem? what's the method to open a popup?