SM-G920i drk failed, what to do?

Operation: Repair DRK
Selected model: SM-G920I
Software version: 32.4

Checking local file... OK
Searching server... OK
Compare local and server file... OK (up to date)
Searching USB Flash interface... COM10 detected
Setup connection... OK
Reading data from phone... OK
Sending data to phone... OK
Sending data to phone... OK
Waiting ADB device... OK
Reading phone info...
Recovery build version: 6.0.1
Boot version: G920IDVS3FRAB
Platform: exynos7420
Boot serial: 11160bedf2383701
Product board: zeroflte
Initialization zTool... OK
Running zTool, please wait...
Start... OK
Initialization... OK
Generate and check client proof... OK
Verify proof by client... OK
Checking DRK status... NG!
Writing DRK... error ()
Done with Samsung Tool PRO v.32.4