Static background for horitzontal slides using parallax

I'm seeing an issue with slides and Parallax
I have a Parallax key

when I have the following code in my templates I can use cover or reveal and everything works

```html

but as soon as I add a slide elements ... the parallex breaks and i get the regular display ... no cover or reveal

````html

Here you can see for your self
This is with the slides as you can see the parallax does not work
http://dev.manufacturedin.it/

when I remove the slide class from the slides the parallax works as required
http://test.manufacturedin.it/

both pages are exactly the same other than the slide class