chaning band to c333 o c332

Dear members,
I need to hear some experiences of changing band to motorola c333 o c332. ... I need to switch from 850/1900 to 900/1800.
I already got the cracked version of VictorGSM and downloaded the flexes from freegsmteam. but i cant do anything... the program reads perfectly but when trying to flex the phone, an alert text come up saying that the flex file performend an unsuported command or method.... what´s that? I tried in Win98 and Win2000.

Anything could help me.
Thanks
Rodo