How to get callback arguments?

Hi, I'm trying to add some callback options, like so:

```
$scope.fpOptions = {
            afterSlideLoad: function( anchorLink, index, slideAnchor, slideIndex){

            }}

    <div full-page options="fpOptions">
    </div
```

However, the callback argument (anchorLink, index, slideAnchor, etc) are coming back as undefined. How can I get the values for these arguments?

Thanks.
