Here is the solution for you:
Samsung J3 SM-J320A [Unlock Only](v6.0.1)(AQC1)
Go here to this link and download the CP Modem & use Odin - CP Flash it.
[This will downgrade your modem to CP version: J320AZTUU2APJ2]
http://forum.gsmhosting.com/vbb/12519953-post11.html
Now use Z3X - Unlock - Read Codes:
Enjoy!
***Tested on my SM-J320A)(v6.0.1)(J320AUCU2AQC1)***
Here is the partial Z3X log:
Operation: Read Codes
Selected model: SM-J320A
Software version: 28.2
Reading phone info... Ok
Model: SM-J320A
AP version: J320AUCU2AQC1
CSC version: J320AATT2AQC1
CP version: J320AZTUU2APJ2 <===== Modem DG to PJ2
Product code: SM2J320AZWAATT
Phone SN: R28H80RVXXX
Unique number: CQ300DC9DD25873
Reading IMEI... Ok