[jQuery] Message didn't disappear in validation plugin

I use jquery validation plugin 1.5.5, and got problem with error
message. They don't disappear when the form is valid or when i use
multiple rules, second rule message didn't show, the message is still
the first rule message.

Here's the code:
$(document).ready(function () {
$('#user_form').validate({
rules : {
username : {
required : true,
min : 4,
max : 32
},
password : {
required : true,
min : 6
},
password_again : {
required : '#password:filled',
min : 6,
equalTo : '#password'
},
name : 'required',
email : {
required : true,
validEmail : true
}
}
});
});

when username is empty, required rule message appear properly, so when
username less than 4 char, but when i fill username with 4 or more
chars the min rule message still appear. email too, when it's blank,
required rule message appear, but when i put invalid email the message
still required rule message.

and here is my validEmail method:
$.validator.addMethod('validEmail', function (value, element) {
var emailStr = value;
var checkTLD=1;
var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|
coop|info|pro|museum)$/;
var emailPat=/^(.+)@(.+)$/;
var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]";
var validChars="\[^\\s" + specialChars + "\]";
var quotedUser="(\"[^\"]*\")";
var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;
var atom=validChars + '+';
var word="(" + atom + "|" + quotedUser + ")";
var userPat=new RegExp("^" + word + "(\\." + word + ")*$");
var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");
var matchArray=emailStr.match(emailPat);

if (matchArray==null) {
//alert("Email address seems incorrect (check @ and .'s)");
return false;
}

var user=matchArray[1];
var domain=matchArray[2];

for (i=0; i<user.length; i++) {
if (user.charCodeAt(i)>127) {
//alert("Ths username contains invalid characters.");
return false;
}
}
for (i=0; i<domain.length; i++) {
if (domain.charCodeAt(i)>127) {
//alert("Ths domain name contains invalid characters.");
return false;
}
}

if (user.match(userPat)==null) {
//alert("The username doesn't seem to be valid.");
return false;
}

var IPArray=domain.match(ipDomainPat);

if (IPArray!=null) {
for (var i=1;i<=4;i++) {
if (IPArray[i]>255) {
//alert("Destination IP address is invalid!");
return false;
}
}
return true;
}

var atomPat=new RegExp("^" + atom + "$");
var domArr=domain.split(".");
var len=domArr.length;

for (i=0;i<len;i++) {
if (domArr[i].search(atomPat)==-1) {
//alert("The domain name does not seem to be valid.");
return false;
}
}

if (checkTLD && domArr[domArr.length-1].length!=2 && domArr
[domArr.length-1].search(knownDomsPat)==-1) {
//alert("The address must end in a well-known domain or two letter "
+ "country.");
return false;
}

if (len<2) {
//alert("This address is missing a hostname!");
return false;
}

return true;
}, 'Email is not valid');