jScrollPane stops to work after the 2nd ajax call

jScrollPane stops to work after the 2nd ajax call

I'm working on a website project written in html5/css/jQuery, which uses
ajax navigation.
You can find it here:
meltingmedia.it/works/alfala
Apart from design, which is awful at the moment because I started today to
code the project.
I coded many sites like this, and the combination between jScrollPane and
ajax calls never gave me problems.
In this specific site, as you can see, for animation needs requested by
the client (every new page has to appear from the right side of the screen
and go near the logo, in a 980px–grid), I had to use two <article>
elements, one which gets "incoming" class and another which gets "current"
class.
Well, when I load the page everything works fine, but when I make the
third click on a menu element (doesn't matter which one), jScrollPane
stops to be casted.
For sure there's a matter of logic or of ordering the events, but I can't
really find it.
Thanks in advance!
PS The layout at the moment is not responsive, and the home page is not
populated yet.