yii2.0：登录界面提交表格后非正常提示 [ 2.0 版本 ]

用户提交登录界面，提交用户表格后输出结果非model里面的message匹配内容？

LoginController.php代码如下：

<?php
namespace backend\controllers;

use yii\web\Controller;
use common\models\LoginForm;
use Yii;


class LoginController extends Controller{
    
    public $layout = 'login' ;
    
    public function actionIndex(){
        
        $model = new LoginForm();

            if($model->load(Yii::$app->request->post() && $model->validate())){
                return $this->redirect(['site/index']);
            }else{
            var_dump(Yii::$app->request->isPost);
            echo "<br>";
            var_dump($model->load(Yii::$app->request->post()));    
            echo "To be continued...";
            }
        
        return $this->render('index',['model' => $model]);
    }
  
}

然后是login/index.php的代码：

<?php
use yii\helpers\Html;
use Yii;

//http://www.yiiframework.com/doc-2.0/guide-output-client-scripts.html
$this->registerCssFile('@web/css/bslogin.css');

?>

<div class="container">
<?=Html::beginForm('','post',['class'=>'form-signin'])?>

        <h2 class="form-signin-heading">Please sign in</h2>

        <?=Html::activeInput('text',$model,'username',['id'=>'username','class'=>'form-control','placeholder'=>'用户名','autofocus'=>true])?>
        <?=Html::error($model,'username')?>

        <?=Html::activeInput('password', $model,'password',['id'=>'inputPassword','class'=>'form-control','placeholder'=>'密码'])?>
        <?=Html::error($model,'password')?>
        <div class="checkbox">
          <label>
            <input type="checkbox" value="remember-me"> Remember me
          </label>
        </div>
        <?=Html::submitButton('登入',['class'=>'btn btn-lg btn-primary btn-block'])?>
<?=Html::endForm()?>
</div>

最后的就是LoginForm：

<?php
namespace common\models;

use Yii;
use yii\base\Model;
use common\models\User;

class LoginForm extends Model{
    
    public $username;
    public $password;
    public $rememberMe = true;
    public $verification;
    
    private $user;
    //登录返回用户信息来储存，用于后面的session，cookies等
    
    public function rules(){
        return [
            [['username','password'],'required','message'=>'{attribute}必须要写入...'],
            ['username','validateUser'],
            ];
    }
    
    public function validateUser($attribute,$params){
        $user = User::findOne(['username'=>$this->$attribute]);
        if(!$user){
            $this->addError($this->attribute,'貌似有错误了额...');
        }   
    }   
}

User Model的部分代码：

    public function rules(){
        return [
            [['username','password','email'],'required','message'=>'{attribute}必须要填写哟，少年'],
            ['username','unique','message'=>'你落后了一步，{value}已经被占用'],
            ['email','email','message'=>'非邮箱地址'],
            ['password','string','min'=>6,'tooShort'=>'密码太短了...呵呵',],
            ['status','in','range'=>[0,1]],
            ];
    }

清空用户输入后，提交信息，输出两个错误信息（username & password）,然后测试只输入用户名不输入密码，还是同样的错误信息，好像用户名那里[输入=没输入]一样。或者全部输入正确用户名及密码，页面也不进行跳转，这是何故？
截图为输入用户命和密码后的输出（控制器添加了var_dump()）：

【疑问】引用User模型的rules不会跟LoginForm的rules冲突吧？