Why my 3gs on 3.1.2 can not unlock ?

[joliano24]

I have 3gs on 3.1.2 and 5.11.07 , i can not unlock it with redsn0w , its get me black screen and nothing elas and i but back 3.1.2 and then keep trying and i used itune 9.0.2,and i try spirit its working but not unlocked the phone, I just need to unlock it for good.

need help plz, what is that I am doing wrong ?

[nagyg]

as far as I know you can unlock your phone only with blacksn0w ...

[i.Annie]

You need to add repo "blacksn0w.com" from Cydia and download Blacksn0w.

Everything you just said they are jailbreaking tools, not for unlocking.