Help to jailbreak iphone4 4.3.1

[vietkool]

I down load the pwnage tool and 4.3.1 ipsw. Ran the pwnage tool and build the custom ipsw. when using itune to restore that custom to my iphone. ther is a error state that the request build eligal something. it won;t let me restore.
Help please

[hardstyle]

These are the steps i took and it worked after long headaches:

Was on 4.1 Unlocked with Ultrasnow using iPad Baseband 6.15

1) Got to www.ih8snow.com (Download Snowbreeze)
2) Download 4.3.1 (for me was 3GS)
3) Create custom ispw using Snowbreeze
4) It will create it on your desktop.
5) Restore it with iTunes (Shift & click restore)
6) Choose your custom (Snowbreeze) ispw
7) It will restore the phone and finish but will still have the (Plug to iTunes BS)
8) Here is the tricky part which worked for me.
On the desktop there should be 3 FILES
Snowbreeze, 4.3.1 ispw, and snowbreeze4.3.1 ispw

9)Download Redsnow
10) Follow directions on the screen and you should choose the stock 4.3.1 ispw you have downloaded and NOT the ispw that Snowbreeze created.
11) The only thing you should have checked is CYDIA and nothing else.
12) Restore it and it should boot up.
Use ultasn0w to unlock.
Now you should have 3GS 4.3.1 / Unlocked.

This is what I did and it worked for me.
Good luck