Cannot show the notification back to browser

I am using designer to create the page, setting a click listener to a button, which can receive the event on the server but when i invoke Notification.show("information", "haha", Type.ASSISTIVE_NOTIFICATION), nothing happen, what did i miss?

Hi,

The notification type ASSISTIVE_NOTIFICATION has the Position.ASSISTIVE, which means it's only accessible for assistive devices (such as screen readers) and invisible for visual users. You can leave out the Type parameter if you wish; Notification.show("message") should be enough.

Hope this helps,
Olli