Default [Q] Unable to unlock bootloader

I just bought the 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 14.3.A.0.757.

Tried both the flashtools and the Sony official way with the unlock code.

Flashtools - gives me the error that the bootloader cannot be unlocked. Tells me to unplug the phone and turn it on.
Sony Official way - under the fastboot - it is confirmed the phone was connected but when I go to enter the code - it says failed <remote: command did not succeed.

I also look through other threads and tried adding a new folder under custom in flashtools with my serial number and unlock code from Sony. This did not work for me. I downloaded the latest adk, flashtools etc... with no luck.

Does anyone else have the same issues? I cannot find an answer in any forum. With a locked bootloader, I am limited to a few stock custom roms that doesn't require an unlocked bootloader.