Почему Yii2 SQL запрос выполняет, а через ActiveRecord нет?

Yii::$app->db->createCommand('SELECT MONTH(reg_date) AS Months, COUNT(*) AS RegCount FROM users WHERE YEAR(reg_date) = YEAR(NOW()) ORDER BY Months')->queryAll();

$this->find()->select(['MONTH(reg_date) AS Months', 'COUNT(*) AS RegCount'])->where(['YEAR(reg_date)' => 'YEAR(NOW())'])->groupBy('Months')->all();