Uncaught TypeError on selection of date?

I have installed the package, am calling it via 

```
Template.seriesAdd.rendered = function() {
    $('.datepicker').datepicker();

}
```

The calendar comes up but when clicking on a date I get the JS error `Uncaught TypeError: Cannot set property 'currentDay' of undefined in jquery-ui-1.9.2.custom.js` - any ideas?
