What should i do??
I ran into this same problem when I unlocked my tablet recently. I found that if I downgraded to Android 4.1.1, firmware version 10.4.4.20, and used the version 7 unlock tool, everything worked like it should. The firmware can be found here:
And I used the method here to downgrade:
I hope this helps.
Thanks goes to Pretoriano80 for compiling the downgrade method and keeping track of the older firmware!