The game event "alien_hurt" dosen't fire when aliens get hurt.

[IAFJaeger]

sv_cheats 1
display_game_events 1

function OnGameEvent_alien_hurt( tEventData )
{
    local hAlien    = EntIndexToHScript( tEventData["entindex"] );
    local flDamage  = tEventData["amount"];
    local hAttacker = GetPlayerFromUserID( tEventData["attacker"] );

    printl( "==> " + hAlien + " " + flDamage + " " + hAttacker );
    return;
}