Shoutbox

What is wrong in here!?

code:

---

<style type="text/css">
#a.about {
    background-image: url(images/about.jpg);
    width: 59px;                   
    height: 41px;                   
    border:none;
    display: block;
    }
#a.about:hover {
background-image: url(images/abouthover.jpg);
}
</style>

<div id="about">
<a class="about" href="http://www.google.pt" ></a>
</div>

---

It isnt working .. :/