can't get roaming with my iphone 3g

[bemania]

hi,

i'm dying trying to get my iphone 3g with simlock to work.
what i have:

iPhone OS Version: 3.1 (with Pawnage Tool 3.1.3)
Bootloader Version: 05.09
Baseband Version: ICE2-05.11.07


i have my iphone unlocked and jailbroken, but i can't get any roaming. i've tried:

installing white sn0w
downgrading to iphone OS Version 3.0 (couldn't downgrade)


does anyone have any tipps how i can get my iphone to work?