json格式的数据，为什么显示不对啊？

[pre]返回的json数据为 {"Boards":[{"BoardID":"1","Subject":"1.征求网上对话栏目的意见","Content":"","IsDisplay":"1","AddDate":"2009-12-9 15:57:13"},{"BoardID":"2","Subject":"2.征求公众留言栏目的意见","Content":"","IsDisplay":"1","AddDate":"2009-12-8 15:57:54"},{"BoardID":"3","Subject":"3网站进行改版整合 征求您的意见","Content":"","IsDisplay":"1","AddDate":"2009-12-7 15:58:06"}]}[/pre]
[pre] $.ajax({
            type: "get",
            url: "Services/GetBoardList.ashx",           
            dataType: 'json',
            async: false,           
            data: "{}",
            success: function(msg) {
               var str_html = "";[/pre][pre]               $.each(msg.Boards, function(i, n) {
               str_html += "<li><a href='downDetails.aspx' class='main'>" + n.AddDate + "</a></li>";[/pre][pre]           }); 
               $("#proaa1").html(str_html);[/pre]
[pre]为什么 n.AddDate 显示的格式是：15:58:06 2009-12-7 [/pre]