Metro PCS A20 Carrier Relocked Successfully Completed - But does not accept AT&T SIM

I used the Carrier Relock service for the Metro PCS A20 (A205U) using MCC/MNC for USA T-Mobile and USA AT&T. The process completed successfully, but when I inserted the AT&T SIM (having MCC/MNC of 310/410) but the phone does not accept it.

Did I miss something?

Thank you!