g925f drk failed code 0x02

Checking local file... OK
Searching server... OK
Compare local and server file... OK (up to date)
Searching USB Flash interface... COM7 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: G925FXXU5EQK5
Platform: exynos7420
Boot serial: 04157df4eb96542a
Product board: zerolte
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