ie8和ie9的问题

代码如下:
var reg = /^(([a-f0-9]){16})+$/;
function test(){
if (reg.test(co)) {
alert(co);
}
}
现在定义一个变量co:
var co = "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";
在页面上有个按钮,onclick设置为"test();",为何在ie8中能弹出显示co的值,ie9中却毫无反应?