Default [Q] Unpacking 14.4.A.0.108 boot.img

Hey I tried to unpack the stock boot.img from the 14.4.A.0.108 firmware for a while now and I couldn't succeed.
Everytime I try to unpack it using an unpackbootimg binary freshly compiled from aosp-tree, I get this error:
Code:
Android boot magic not found.
I googled a bit about this problem, but I coudn't find the solution. Is there something sony is doing to prevent us from unpacking their bootimages and if yes, is there any way to bypass?

Thanks

EDIT:

I could solve the problem using FlashTool
 

Devices:
Samsung Galaxy S II Plus NFC

Current works:
OmniROM I9105(P): http://forum.xda-developers.com/show...php?p=49953943
Cyanogenmod 11 I9105(P): http://forum.xda-developers.com/show....php?t=2568665
MoshKernel I9105(P): http://forum.xda-developers.com/show....php?t=2615010

Donation:
Please see the paypal email in my profile, thanks.