Why is the transaction not opening?

Question

Yii

Hello!
Why is the transaction not opened with the following code?

$transaction = Yii::$app->db->beginTransaction();
Yii::$app->db->createCommand('DELETE FROM profiles WHERE id = 1000')->execute();
$transaction->rollBack();

And this is how it works:

$transaction = Yii::$app->db->beginTransaction();
$transaction->begin();
Yii::$app->db->createCommand('DELETE FROM profiles WHERE id = 1000')->execute();
$transaction->rollBack();

What can be wrong?