jQuery Ajax响应&“未定义&"使用Internet Explorer

我遇到了jquery ajax请求的情况.

I've got a situation with jquery ajax requests.

<script type="text/javascript">
$(document).ready(function() {
    $.ajax({
        type: "POST",
        async: false,
        cache: false, 
        url: "/ajax/script.php",
        data: { display: 'user', user_id: '1'}
    }).done(function( msg ) {
        if (msg !== "") {
            alert(msg);
        }
    });
});
</script>

使用Chrome& Firefox我有由脚本/ajax/script.php生成的html代码 使用IE8(我没有尝试过6、7和9+)，我有Undefined

With Chrome & Firefox I've html code generate by the script /ajax/script.php With IE8 (I've not tried with 6, 7 and 9+) I have Undefined

有人知道该如何解决吗?

Do someone knows how to fix that?

我正在使用jquery 1.7.2

I'm using jquery 1.7.2