后台有2个控件(button和自定义验证控件)，点击button怎么先调用自定义验证控件

问题描述

protectedvoidCustomValidator1_ServerValidate(objectsource,ServerValidateEventArgsargs){stringuserId=userName.Text.Trim();if(CatalogAccess.GetMemberExit(userId)!=null){args.IsValid=false;}else{args.IsValid=true;}}protectedvoidbtnSave_Click(objectsender,EventArgse){stringmemberId=userName.Text.Trim();stringmemberPassword=userPassWord1.Text.Trim();stringmemberEmail=userEmail.Text.Trim();stringmemberNickName=userNickName.Text.Trim();stringmemberQuestion=userQuestion.Text.Trim();stringmemberAnswer=userAnswer.Text.Trim();CatalogAccess.AddMember(memberId,memberPassword,memberEmail,memberNickName,memberQuestion,memberAnswer);}求大能帮忙，谢谢了