When visiting standard treasure chambers and adding resources, the player sees nice pictures depicting them.
How can this be achieved manually if the treasure chamber is scripted?

(The manual says that ChangeResource
Changes the amount of a specified resource for the player who owns the specified hero. At the same time, a "flying" message appears from this hero, indicating the change in the resource.
But if you write it in a script, it doesn't work/Attempt to call nil value ''ChangeResource).
Version 3.1