Default Sony Xperia S root

Hi

I am trying to root my sony xperia S on 6.2.B.1.96 using this guide:

http://forum.xda-developers.com/show....php?t=2417672

Sorry if this is noobish, but I cant seem to flash the first kernel (step one), it just says it is unrootable and finishes.. When I turn my phone back on nothing has changed.

Please help