ul > li:nth-child(1) > a /// NOT WORKING IN IE8

[divstudio]

Hello

i'm working on a website.
The menu's items have different colors, submenus too.
I'm using li:nth-child() to do this

I tried this but did not work in IE8 :
#menudesktop > ul > li:nth-child(1) > a{
color:#1d1d1f;
}

It's strange because this one is working :
div.event:nth-child(odd){
background-color:#f5f5f5;
}

I tried only with jQuery then i added Mootools...
I load css3-mediaqueries.js before selectivizr.js

i tried to use same css rules without media queries but did not work

here's a live demo :
http://divstudio.fr/test/abpieh/index.html

thx for your help !