js 新手，求答疑 bug
HTML和JS的代码分别如下
程序代码：<!DOCTYPE HTML>
<html>
<head>
<meta charset=utf-8>
<style type="text/css">
#div1{
width: 200px;
height: 200px;
background-color: red;
}
</style>
</head>
<body >
<script src="1.js">
</script>
<input type="button" value="TYe" onclick="change('yellow')" />
<input type="button" vale="TBlu" onclick="change('blue')" />
<input type="button" value="TBla" onclick="change('black')" />
<div id='div1'>This is a change sample</div>
</body>
</html>
-----------------------------------------以下是1.js代码------------------------------------------
function change (argument) {
var oDiv =document.getElementById('div1');
oDiv.style.background=argument;
}但是在浏览器中打开HTML时，第二个button的value值并不显示出来，求解惑
