Have you unlocked your device using Olipro Titan Unlocker 1.20? You can see if you've unlocked it when you try to flash a ROM and the device goes into bootloader mode (various layers of colors on the screen). It should say TITA-Olipro 1.20 or something like that. This shows that your device is unlocked with Olipro's Titan Unlcoker. If you haven't unlocked your device, then the unlocker is in the following thread:
http://forum.ppcgeeks.com/showthread.php?t=9093
Hope that helps.