samsung g920a unlock problem

read code faild

Please wait, generating hash codes file, this can take few minutes… OK
Waiting ADB device… OK
Reading phone info…
Model: SAMSUNG-SM-G920A
Android version: 5.0.2
Product code:
Phone version: G920AUCU2AOF4
PDA version: G920AUCU2AOF4
CSC version: G920AATT2AOF4
CSC country code: USA
CSC sales code: ATT
HW version:
Phone S/N: 00000000000
Modem board: SHANNON333
RF cal date:
IMEI:
Checking Super user right… false
This model not supported for auto root
Done with Samsung Tool PRO v.24.2

direct unlock faild

Waiting ADB device… OK
Reading phone info…
Model: SAMSUNG-SM-G920A
Android version: 5.0.2
Product code:
Phone version: G920AUCU2AOF4
PDA version: G920AUCU2AOF4
CSC version: G920AATT2AOF4
CSC country code: USA
CSC sales code: ATT
HW version:
Phone S/N: 00000000000
Modem board: SHANNON333
RF cal date:
IMEI:
Checking Super user right… false
This model not supported for auto root

Done with Samsung Tool PRO v.24.2

any one tell me how to root this phone version is 5.0.2