麻烦大神们帮我看看哪里写错了，点击按钮没反映
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script type="text/javasctipt">
function rec() {
var score;
score=85
if(score>=90)
{
document.write("你真棒！");
}
else if(score>=80)
{
document.write("真不错！");
}
else if(score>=70)
{
document.write("继续努力！");
}
else
{
document.write("你得非常努力！");
}
}
</script>
</head>
<body>
<input name="button" type="button" onClick="rec()" value="按 钮" />
</body>
</head>
<body>
</body>
</html>
