999_T1Tutorial Error - Freya how to fix it?

[Stewie]

 

I have an error wich show sometime's... its in one of quests - 999_T1Tutorial .

 

 

Here is line 237....

   Ex = int(qs.get("Ex"))

Here is part of code.

 def onKill(self,npc,player,isPet):
   if Config.DISABLE_TUTORIAL :
     return
   st = player.getQuestState(qn)
   if not st : return
   qs = st.getPlayer().getQuestState(qnTutorial)
   if not qs : return
   Ex = int(qs.get("Ex"))
   if qs != None :
      if Ex in [0,1] :
         st.playTutorialVoice("tutorial_voice_011")
         st.showQuestionMark(3)
         qs.set("Ex","2")
      if Ex in [0,1,2] and st.getQuestItemsCount(6353) < 1 :
         st.dropItem(npc,player,6353,1)
         st.playSound("ItemSound.quest_tutorial")
   return

QUEST       = Quest(999,qn,"Kamael Tutorial")

 

 

What to do? Please help :D