I am using IE9, VS2010 with CSS2.1

I just want to add a round button. So I have this.

.round-button
{
width: 960px;
background-color: #fff;
margin: 20px auto 0px auto;
border: 1px solid #496077;
border-radius: 0px 0px 50px 50px;
-moz-border-radius: 0px 0px 50px 50px;
-webkit-border-radius: 0px 0px 50px 50px;
behavior: url(http://mysite/PIE.htc);
}

When I open it in Chrome, it looks good, but not in IE9. Also, 'behavoir' is not a known CSS property name (I believe it's normal)

Please help, thanks in advanced.

zd.