after 4 days trying to unlock the phone, finally i did it. The Dev_team just release the new version of yellowsn0w 0.96. Here is what i did: I just upgrade to 2.2 FIRMWARE then did the QuickPwn. and then go to Cydia to install the new version of yellosnow 0.96. after that go to reset net work. after reboot the phone, it will serching for the signal. Next the Tmobile will come up.
Thanks Dev_team .... it work well in new version. ... you don't need to do any extra step.