Xperia Z fails to unlock bootloader topic

When I run cmd fastboot.exe -i 0x0fce getvar version I get

Quote:

version:0.5 finished. total time -0.000s

Then I run fastboot.exe -i 0x0fce oem unlock 0xKEY (With my key from Sony) and I get
...

Quote:

FAILED <remote: command not allowed> finished. total time: 0.000s

How do I fix this to unlock the boot loader?!?!

Quote:

Bootloader unlock allowed: Yes