Missed in [4361]

fix
java.lang.NullPointerException
<------>at com.l2jserver.gameserver.model.zone.type.L2SiegeZone.onEnter(L2SiegeZone.java:95)

L2_GameServer/java/com/l2jserver/gameserver/instancemanager/TerritoryWarManager.java

@@ -858,6 +858,7 @@ public class TerritoryWarManager implements Siegable
 			{
 				t.changeNPCsSpawn(1, true);
 				fort.resetDoors(); // Spawn door
+				fort.getZone().setSiegeInstance(this);
 				fort.getZone().setIsActive(true);
 				fort.getZone().updateZoneStatusForCharactersInside();
 			}