problem with setflash in backend

good afternoon to all

I have the following question, I am using advanced mode

when I try to use this in the backend

Yii :: $ app-> getSession () -> setFlash (‘success’, ‘message content’);

does not work: S

any suggestions on the frontend works perfectly?

I have noticed this problem too. Maybe it is some hidden feature that we don’t know about :D, but it is very strange. I would like to know why this is happening too. I also noticed that in some situations, when you log in using frontend login page, you end up being logged in into backend application.