unlocking Lumia 820 RM-825


i am trying to unlock Lumia 820 RM-825
– i flashed different product code
– battery fully charged
– updated configuration with Configurator
Code:

Connecting to server...

Credits: 74

WP8 Unlock Started
Connecting to server...
Connected
Authenticating...
Authenticated
Checking Client version...
Client version is valid
Processing Step #1


always same error (server 0600)

please advice