HELP NEEDED... updated my 3gs to ios5 and i can not unlock it!!

i upgraded my old bootrom 3gs modem firmware 05.16.05 from ios 4.3.3 to ios 5.. i did the jailbreak went to cydia and installed Ultrasn0w but it did not unlock the phone !! now downgraded back to 4.3.3 and jailbreak it again went to cydia and installed ultrasnow and still not working!! when i try to manually search for a carrier i get this error ( Unable to load network list ) ... anyone please can tell me what to do?!