Project for tomorrow (Firebase DataChanged event not working)

plz help me tommorow i have to submit my project the firebasdDB1.Datachanged block is not working please any help

each time we change in our firebase the label1.text does not change.
no errors just it does not change.

Are you using Firebase Authentication for users ? If so, what are your Firebase rules? Can one user access another users data ?

Also see here:

In essence, a user must use the firebase blocks at least once to do something with the database, in order to activate the dataChanged event and for it to work. (There must also be something in the database to be changed, otherwise the event will not fire, and generate an error)

what do you mean by Firebase Authentication for users.
i set the rules write and read both true