How to display admin noticiation from custom module

[Przemysław Suszek]

Good day,

I want to display some custom information in my custom module. In _construct method I add

    public function __construct()
    {

        $this->checkForUpdates();
    }

And:

    public function checkForUpdates(){
        $this->adminDisplayWarning('Your message'); 
    }

In debug I don't see any error. but in admin panel I don't see this message. Above code I write for Prestashop 1.7. Where is the problem?

Kind regards