.ajax always return error

.ajax always return error


hi all,
I got an ajax code, when i run it in local it goes fine, but when i
upload to server it always gets to error status
i checked the status it does show 200,
can anyone help me to fix this problem
$.ajax({
        url: 'game_func.php?act=ioratio',
        dataType: "json",
        success: function(json) {
            if(json.callback == "done")
            {
                teamcon.value = json.newcon;
                document.getElementById("team1_io").value = json.newio1;
                document.getElementById("team2_io").value = json.newio2;
            }else{
                if(json.value == "concede")
                {
                    alert('球投輸入錯誤!!');
                }
            }
        },
        error: function(xhr) {
            alert(xhr.status);
        }
    });
and this is the json string return
{"callback":"done","newcon":"2.5","newio1":"0.850","newio2":"0.850"}