Bootloader unlock problem - Kiano Slimtab 7 3GR

Hello Guys, im fighting with Kiano slimtab 7 3gr for a few days.

First of all i made a root form this solution: http://forum.xda-developers.com/andr...t/mod-t3175515 and it worked.

Now i want to unlock bootloader and install TWRP, but there are some problems. I have estabilished ADB and Fastboot connection with no problems. But when i go into fastboot mode and im trying to unlock bootloader via fastboot oem unlock commad it doeasn't work. Could someone help me?

Code:

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root@kali:~# fastboot devices
0123456789012345        fastboot

root@kali:~# fastboot flash recovery recovery.img
(bootloader)  recovery partition type: raw
target reported max download size of 1019215872 bytes
sending 'recovery' (14090 KB)...
(bootloader)  Device is locked, cannot perform flash in fastboot
(bootloader)  Please use the below command to unlock first:
(bootloader)  > fastboot oem unlock
FAILED (remote failure)
finished. total time: 0.026s

root@kali:~# fastboot oem unlock
...
FAILED (remote: couldn't change state!)
finished. total time: 0.022s
root@kali:~#

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