Can someone explain why I can't jailbreak my IPod?

I'm trying to use jailbreak 4.3.3 on my IPod touch 4g thru redsn0w, I have downloaded the 4.3.3 update and everything, I put it in DFU mode and then I get to the point where it says "Exploiting with limera1n", and then my Ipod magically turns on when that step starts and I can't jailbreak it. Can someone tell me why this happens and how to fix it?