New Post/old post changing image

I have tried to find help on that forum and I did, but following instructions found I dont quite get the expected result...
Here is what i have done:

Code in stylesheet.css

/****************************************************************/
/* 10. POST STATUS INDICATORS */
/****************************************************************/

/* 10.1 These are the post status indicators which appear at the left of some tables.
.inew = new posts, .iredirect = redirect forums, .iclosed = closed topics and
.isticky = sticky topics. By default only .inew is different from the default.*/

DIV.icon {
    FLOAT: left;
    MARGIN-TOP: 0.1em;
    MARGIN-LEFT: 0.2em;
    DISPLAY: block;
    BORDER-WIDTH: none;
    WIDTH: 20px;
    HEIGHT : 20px;
}

and code in stylesheet.cs.css

/****************************************************************/
/* 5. POST STATUS INDICATORS */
/****************************************************************/

/* These are the post status indicators which appear at the left of some tables.
.inew = new posts, .iredirect = redirect forums, .iclosed = closed topics and
.isticky = sticky topics. The default is "icon". By default only .inew is different.*/

DIV.icon { background-image: none}
TR.iredirect DIV.icon { background-image: none }
TR.iclosed DIV.icon { background-image: none }
TR.isticky DIV.icon { background-image: none }
TR.inew DIV.icon {background-image: url(http://deusl3r.free.fr/masque.gif) }

But i dont get anything...What did i do wrong? It really does not change anything...