Remember me in yii - yii

Question

How to Work Remember me Function in Yii.
My Coding.
In Config/Main.php
'user'=>array(
// enable cookie-based authentication
'allowAutoLogin'=>true,
),
UserIdentity.php
public function authenticate() {
$this->errorCode = self::ERROR_NONE;
$user = User::model()->find("username = :username or email=:username", array(":username" => $this->username));
if ($user === null) {
$this->errorCode = self::ERROR_INCORRECT_CREDENTIAL;
} else {
if($user->is_active != 1){
if($user->activation_token_used == 0){
$this->errorCode = self::ERROR_NOT_ACTIVATED;
}
else{
$this->errorCode = self::ERROR_ACCOUNT_INACTIVE;
}
}
else{
$isCorrectPwd = ($user->password !== Yii::app()->mclass->encryptPwd($this->password)) ? false : true;
if ($isCorrectPwd) {
if($user->is_deleted == 1){
$this->errorCode = self::ERROR_ACCOUNT_DELETED;
}
elseif($user->is_active != 1){
if($user->activation_token_used == 0){
$this->errorCode = self::ERROR_NOT_ACTIVATED;
}
else{
$this->errorCode = self::ERROR_ACCOUNT_INACTIVE;
}
}
} else {
$this->errorCode = self::ERROR_INCORRECT_CREDENTIAL;
}
}
}
if ($this->errorCode == self::ERROR_NONE) {
$this->_id = $user->id;
$this->_isAdmin = ($user->user_type == Yii::app()->const->ADMIN_USER_TYPE) ? true : false;
$this->setState('user_type', $user->user_type);
$this->setState('username', $user->username);
}
return !$this->errorCode;
}
Model Class
public function login() {
if ($this->_identity === null) {
$this->_identity = new UserIdentity($this->username, $this->password);
$this->_identity->authenticate();
}
if ($this->_identity->errorCode === UserIdentity::ERROR_NONE) {
$duration = $this->rememberMe ? 3600 * 24 * 30 : 0; // 30 days
Yii::app()->user->login($this->_identity, $duration);
return true;
}
else
return false;
}
Whats Wrong in my code,Why Remember me not working.
And Also what is the difference between browser remember me and in that site remember me in yii.once i remember me checked and then login and also logout site.Again i run the login url mean both username and password are placed i am right?