background-image is not displayed in iphone

I don't know why the 'background-image' I set works fine in all browsers but it doesn't in Iphone's safari browser (wich is the one I need),
This is the relevant style for the question
    /
ESTILOS PARA SINGLE JOB
    /

   /*Deleting all styles that dont take any effect with the question*/

    #panel.right ul.visible li a span.liLeft{
width:95px;
float:left;height:100%;display:block;
position:relative;
right:40px;
/*HERE I INIT THE STYLE OF THE BACKGROUND IMAGE BUT I DONT SET THE URL*/
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
background-size: cover;
z-index:10;
    }

    #panel.right ul.visible li a span.liRight{
background:black !important;
color:#fff;

    }

    #panel.right ul.visible li a span.liRight{
z-index:9;
    }

    #panel.right ul.visible li#blue a{
border-color:#0C7CC3;
    }
    #panel.right ul.visible li#pink a{
border-color:#C21B7B;
    }
    #panel.right ul.visible li#orange a{
border-color:#E83B35;
    }

    /*  HERE i set the urls for the different Id's and i can't see them in the iphone  */
    #panel.right ul.visible li#blue a span.liLeft{

background-image:url('http://piscolabis.info/licht/img/azul.png');
    }
    #panel.right ul.visible li#pink  a span.liLeft{
background-image:url(../img/rosa.png);
    }
    #panel.right ul.visible li#orange  a span.liLeft{
background-image:url(../img/naranja.png);
    }

    /* deleting more styles*/

you can check the online code at http://jsfiddle.net/6dK3T/2/ or at http://piscolabis.info/job_single.html
As you can see i set a full path URL only so you can see that the image is in the server (and in any desktop browser), but i don't know why the image is still not displayed in the iphone
( it's displayed exactly like the other two i didn't set absolute path (and as they are not in jsdfiddle they don't work))
Is it because of the background-image? is it because the position:relative?  
any idea why is this happening? 
-EDIT-
should look like this

Isn't this like a mistery?

I managed to get it to show on my iPhone by tweaking your styles a bit : 
#panel.right ul.visible li a span.liLeft{
     width:95px;
     float:left;
     height:100%;
     display:block;
     position:relative;
     margin-left: -40px;
     margin-right: 40px;
     -webkit-background-size: cover;
     -moz-background-size: cover;
     -o-background-size: cover;
     background-size: cover;
     z-index:10;
}

#panel.right ul.visible li a span.liRight {
     background:black !important;
     float: left;
     color:#fff;
}

The problem was the same with Safari on OSX. By removing the     
 right: 40px;

in the CSS the images started showing.
http://jsfiddle.net/5sX54/9/

I had a similar problem with an image that was 2200x2500px but only 130kb and didn't load.
It seems like smartphones and tablet don't load images wider than 1024px.
So try to load a smaller image for specific devices and it should works OK.
Edit: I also removed the resizes on the image and the big image appeared. In my case I removed background-size (or put it to auto).