Jquery自动完成,该怎么解决

Jquery自动完成
大家帮忙给看看，我就想做一个像百度是的，输个字符就出来好多可供选择的，现在后台一输出就变成JSON数据在前台界面显示出来了，咋回事啊，错哪了？

JScript code

$(document).ready(function() {        $("#suggest1").autocomplete("default.aspx",{            minChars:1,            max:100,            matchSubset:1,            matchContains:1,            cacheLength:10,            dataType:'json',            parse:function(data){                var parsed = [];                for(var i=0;i<data.length;i++)                {                    parsed[parsed.length]={                        data:data[i],                        value:data[i].city,                        result:data[i].city                    };                }                return parsed;            },            formatItem:function(data){                return "<div>"+data.city+"</div>";            },            formatMatch:function(data){                return data.city;            },            formatResult:function(data){                return data.city;            }        });//.result(function(event, data, formatted) {//         $("#XYhidden").val(data.id);    });

C# code

{"[{"id":"1","city":"Aberdeen"},{"id":"2","city":"Ada"},{"id":"3","city":"Adamsville"},{"id":"4","city":"Addyston"},{"id":"5","city":"Adelphi"},{"id":"6","city":"Adena"},{"id":"7","city":"Adrian"},{"id":"8","city":"Akron"},{"id":"9","city":"Albany"},{"id":"10","city":"Alexandria"},{"id":"11","city":"Alger"},{"id":"12","city":"Alledonia"}]}