Why won't my iPod Touch let me jailbreak it?

Every time I try to jailbreak my iPod, whether its using QuickPWN, redsn0w, or QuickFreedom, there are problems. In QuickPWN, it gets sorta there, but i have trouble putting in the firmware. In redsn0w, my screen doesn't change, AT ALL. In QuickFreedom, as i get to the create custom firmware step, and I put my iPod into DFU mode, it doesn't detect it! HELP!!!