No flare in Bloody Crestwaves

At the start of the Age of Empires II campaign The Mountain Royals, Thoros II, 4/Bloody Crestwaves I don’t see how to send the slightest flame, which prevents me from continuing.
The other Royals Mountains scenarios and campaigns have all been successful.
Can anyone help me ?
Best regards.

there is a symbol next to your minimap that looks like fireworks. click that, then click where you want to send the flare