里面的函数怎么onclick调用不起来，求高手解析~
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.<html xmlns="http://www.
<head>
<title></title>
<script type="text/javascript" language="javascript">
function getsum() {
var n1 = document.getElementById("Text1").value;
var n2 = document.getElementById("Text2").value;
if (n1 == "" || n2 == "")
alert("请输入数字");
return;
}
var sum = parseFloat(n1) + parseFloat(n2);
document.getElementById("Text3").value = sum;
</script>
</head>
<body>
请输入一个数：<input id="Text1" type="text" /><br/>
请输入第二个数:<input id="Text2" type="text" /><br />
<input id="Button1" type="button" value="求和" onclick="getsum()" />:<input id="Text3" type="text" /><br />
</body>
</html>
