Can't Typing Thai Alphabet

 Hello I'm having issues with the recently released Sims 2 Legacy game. This is a problem I've had since I bought the game. 

 The problem is that I can't type Thai alphabet in character names or family stories, even though my game is in Thai. I tried the method from MBaturina10 forums. But it still doesn't work. My Thai letters are still invisible.  

  If anyone has a solution to this problem please tell me. Thank you for your help.