Need help with sound trigger

Im a newbie on the warcraft 3 map editor, me and my friends are just making a map for fun but i need help with this trigger:

Events:
Unit - castle 0001 <gen> is attacked

Conditions:

Actions:
Player Group - Pick every player in Playergroup - Player 2 Blue and do (Sound - Play Host_Station_Under_attack <gen>]

But when i try this trigger in the map all players can here it, why?
Plz help me