CSS not working in IE8

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C#

ASP.NET

Hi Friends I am working on a Tab Structure....

For that i m using ul and li tags.....

The requirment is to apply rounded corner to the tabs i have created a css in there i have applied a class as follows......

.TabbedPanelsTab {
    position: relative;
    top: 1px;
    float: left;
    padding: 4px 15px;
    margin: 0px 1px 0px 0px;
    font: bold 11px sans-serif;
    background-color: #fff;
    list-style: none;
    color:#000;
    border-left: solid 1px #569200;
    border-bottom: solid 1px #569200;
    border-top: solid 1px #569200;
    border-right: solid 1px #569200;
    -moz-user-select: none;
    -khtml-user-select: none;
     -moz-border-radius: 20px;
    -webkit-border-radius: 20px;
    -khtml-border-radius: 20px;
    border-radius: 20px;
    cursor: pointer;
}

it working on the Chrome, and in mozila also but Its not working on the IE....
I m using IE8 version.....
So plz help me out......