G925T Unlock problem

Any idea ?

Waiting ADB device… OK
Reading phone info…
Model: SM-G925T
Android version: 5.1.1
Product code: SM2G925TZKATMB
Phone version: G925TUVS3DOJC
PDA version: G925TUVS3DOJC
CSC version: G925TTMB3DOJC
CSC country code: USA
CSC sales code: TMB
HW version: REV0.2
Phone S/N: R58GB25Q5MA
Modem board: SHANNON333
RF cal date: 20151120
Checking Super user right… true
Check version… OK
Initializating zTool… error (0)
Done with Samsung Tool PRO v.24.0

With version 23.0 it gives error 7.7.8