After open the roof to ease the birds flying in, some how it does not help much. I asked one of my friend opinion. He told me that there are a few sub-species AF, some build nests all the year and some only make nest at certain session. So, he suspect mine is belong to the later one.
Anyway, I believe there are few more things that I can try out. I will spend more time at my BH in the coming visit to implement those changes.
For those people in the same situation as me, remember "You are not consider failures if you never give up". Keep trying...Good Luck.