JSon数据错误

嗨，我有一个Ajax Json调用的代码是

        $.ajax({
            type: "POST",
            contentType: "application/json; charset=utf-8",
            url: "Voyage.aspx/VoyageVessel_Set",
            data: "{Action:'" + "Set" + "',VesselID:'" + "1" + "',VoyageMasterID:'" + "1" + "',StartTerminalID:'" + "1" + "',LastTerminalID:" + "" + ",EffectiveStartDate:'" + "09/09/09" + "',EffectiveEndDate:'" + "09/09/09" + "',PreviousVoyageID:'" + "1" + "',NextVoyageID:'" + "1" + "',DefaultVoyage:'" + "0" + "',Status:'" + "true" + "'}",
            async: true,
            dataType: "json",
            success: function (data) {
                try {
                    alert("Success for ADD button");
                    //  $('#dvVesselTaggerInfo').html(html);
                } catch (ex) {
                    alert(ex);
                }
            },
            error: function (msg) {
                alert(error);
            }
        });

因为我试图给我的方法的数据不调用，我希望我已经写在正确的格式，但我仍然不能理解是什么问题，可以有人帮助我。