Error : reference error data is not defined json

function SaveRecords() {
            var fname = $('#txtFirstName').val();
            var mname = $('#txtMiddelName').val();
            var lname = $('#txtLastName').val();

            var UserRegistration = {};
            UserRegistration.FirstName = fname;
            UserRegistration.MiddelName = mname;
            UserRegistration.LastName = lname;

            $.ajax({
                type: "POST",
                url: "Login.aspx/SaveRecords",
                data: JSON.stringify({ 'UserRegistration': UserRegistration }),
                contentType: "application/json; charset=utf-8",
                datatype: "json",
                success: function (data) {
                    var result = data.d;
                    if (result == 1) {
                        alert("Record Saved Successfully...!");
                        window.location.reload();
                    }
                    else {
                        alert("oops!! Something Went Wrong..");
                    }
                }
            })
        }