Default [Q] Phone not allowed mm#6 error message

Phone: SHG-I317
Carrier: AT&T
Current Firmware: 4.1.1

Hey guys, I purchased this phone and have yet to officially activate it. I downgraded from 4.1.2 so that I could unlock it to work on other networks. I did the unlock procedure and I attempted to put in a METRO PCS Sim card but I get: Phone not allowed mm#6. The phone is not blacklisted as Ive checked numerous sites online and even went to a AT&T store and they were able to pop a AT&T Sim card in and it worked just fine.

I tried to search this issue but the only thing I can come up with was that it could possibly be blacklisted but Ive ruled out that possibility for now.

Could it be that the unlock was unsuccessful and I need to do it again? But then how am I supposed to know that it was successful without another carriers sim card? is there something that changes in the settings or something?

Thank you very much for your help.