Thanks. One important issue which has been raised before

is that I didn't file I-485-based EAD prior to my petitio for OPT. This might be a critical factor for a sucess to get OPT during the AOS. Obviously, I didn't put the A# on my OPT application. Rather, I put I-94 number.

Anyway, I just want to share some info with anyone who may need it. I got quite bit useful info from here too.