I'm using the [jQuery TOOLS - The missing UI library](http://flowplayer.org/tools/).
For tooltip on all input fields I do

```
            $("#univers :input").tooltip({
            effect: 'slide',
            position: "center right",
            offset: [-2, 10],
            effect: "fade",
            opacity: 0.5,
            tip: '.tooltip'
        });

```

But I would like to show tooltip **only if input field is empty**. So I did

```
                $("#univers input:text[value=""]").tooltip({
            effect: 'slide',
            position: "center right",
            offset: [-2, 10],
            effect: "fade",
            opacity: 0.5,
            tip: '.tooltip'
        });

```

But this one doesn't work !

Any idea ?