Default Unable to unlock bootloader

I just bought the Z2 phone which is UNBRANDED and check that the BOOTLOADER can be UNLOCKED under the configuration menu. The phone is rooted which I verified through a program. Using Android 4.4.2, Build 17.1.2.A..0.314

Tried the flashtools to unlock it

Flashtools - gives me the error that the bootloader cannot be unlocked. Tells me to unplug the phone and turn it on.

Any help?