Last year, I got the same experience like you. My son is shy and takes time to warm up. I got an interview in Kowloon Tong Think around October. He didn't make any response, not even telling his name or age. Of course, he is rejected. Then I called the school again in March. They offer us another interview in April. This time we even got an offer for AM school. If you really like that school, just keep trying ask for the offer. Don't give up.
Good luck!