Problem downgrading baseband 6.15

[xavier1970]

Hi guys
I m having problems downgrading ipad baseband 6.15 on a 3g with iOS 4.2.1. I ve tried different versions of redsn0w but none have done the job right. One of them bricked the baseband completely so badly that didnt have comm, so had to install ipad bb again. The other didnt do anything at all, it did the whole process but when I checked it was still 6.15
Can anyone tell me what should I do to get it downgraded?
Is it an issue with redsn0w versions?
Need help please

 

[willerz2]

Did you try selecting the iOS 4.2.1 IPSW for the iPhone 3G before downgrading? And make sure your 3G is in DFU mode.

 

[xavier1970]

Yes, I did select the IPSW and put the iPhone in DFU