Question: **UPDATE**  

I have reverted back to Jquery 1.3.2 and everything is working, not sure what the problem is/was as I have not changed anything else apart of the jquery and ui library versions.

**UPDATE END**

I having an issue with the [JQuery UI datepicker](http://jqueryui.com/demos/datepicker/). The datepicker is being attached to a class and that part is working but the datepicker is not being displayed.

Here is the datepicker code I am using and the inline style that is being generated when I click in the input box that has the class ".datepicker". 

```
$('.datepicker').datepicker({dateFormat:'dd/mm/yy'});

display:none;
left:418px;
position:absolute;
top:296px;
z-index:1;

```

If I change the display:none to display:block the datepicker works fine except it dosen't close when I select a date.

Jquery libraries in use:

* jQuery JavaScript Library v1.4.2
* jQuery UI 1.8 jQuery UI Widget 1.8
* jQuery UI Mouse 1.8 jQuery UI
* Position 1.8 jQuery UI Draggable 1.8
* jQuery UI Droppable 1.8 jQuery UI
* Datepicker 1.8

Answer: 
Try putting the z-index of your datepicker css a lot higher (eg z-index: 1000).
The datepicker is probably shown under your original content.
I had the same problem and this helped me out.
In case you are having this issue when working with WordPress control panel and using a ThemeRoller generated theme - be sure that you are using 1.7.3 Version of theme, 1.8.13 will not work. (If you look closely, the element is being rendered, but .ui-helper-hidden-accessible is causing it to not be displayed. 

Current WP Version: 3.1.3