HELP ME! Wont go to DFU mode!

[XxPlzzJailbreakMexX]

my friend has the same ipod as me, iPod Touch 2g MC model, he got the greenpois0n jailbreak on his first try. but mine just turns back on when i try to put into DFU. I follow the directions on the screen and ive done it over 20 times. if u know any applications or scripts that will send it into DFU mode then plzzzz comment with the link. i need help! thank you for your help.

[i.Annie]

Do a restore first, then try GP again.