This is a little crazy

Ok...I am at our bakery and I greet a female employee and she says nothing back. I asked a woman who was with me to speak to her in Thai and the women does not reply to her either. I went back to the home and asked why the woman would not greet me or the other woman and they said, "She is a little crazy do not worry". They called the bakery and asked the woman why she did not greet us and she said, "I am sorry, I thought they were ghosts". Ahhhh, the old I am seeing ghosts execuse. I think I need to consult my "How to manage people" book on this one.