jQuery在输入下验证发布错误消息

你好stackoverflow成员。我需要在每个未通过验证的输入下显示由jQuery验证插件生成的错误消息。如何在errorPlacement函数中设置此消息？这是我的代码。

$(document).ready(function(){
    var base_url = window.location.origin;
    //Preiau mesajele de erroare pentru form 

    var language = $("#lang").val();
    var firstname = $("#fname").val();
    var lastname = $("#lname").val();
    var email_req = $("#em_req").val();
    var email = $("#em").val();
    var email_remote =$("#email_remote").val();
    var country = $("#cntry").val();
    var city = $("#cit").val();
    base_url=base_url+"/admin/"+language+"/adduser/";
    $("#success_message").hide();
    $("#addnewuser").validate({

            rules:{
                firstname: {
                    required:true,
                },
                lastname:{
                    required:true,
                },
                email:{
                    required:true,
                    email: true,
                    remote: {
                        url: base_url+"checkemail",
                        type: "POST",
                        datatype:"JSON",
                        data:{
                            email: function(){
                                return $("#email").val();   
                            }
                        },
                    }
                },
                country: {
                    required:true,
                },
                city:{
                    required:true,
                },
            },

            messages:{
                firstname: {
                    required:firstname,
                },
                lastname:{
                    required:lastname,
                },
                email:{
                    required:email_req,
                    email: email,
                    remote:email_remote,
                },
                country: {
                    required:country,
                },
                city:{
                    required:city,
                },
            },
            errorPlacement:function(error,element){

            },
            submitHandler: function(form){
                        $.ajax({
                            type: "POST",
                            url:base_url+"addUser",
                            dataType: "html",
                            data: $("#addnewuser").serialize(),
                            success: function(data){
                                if(data == true)
                                {
                                    $("#success_message").show();
                                }       
                            }
                        });
                    return false;
                }

        });
});