We resolve MAC address sending special request to target machine throw "RARP" part of TCP/IP protocol. If your machines coonfigured to hide they MAC address - our program can't show it.
Also, if your machines are nehind proxy or router, it can hide or place it's own MAC address insted of target machine's.
Try to run command shell, then perform "ping <target machine IP>", and then "arp -a". If MAC address is not present in the table shown - then it can't be resolved. If it exsists, but our program shows it as 0 - please e-mail me at firstname.lastname@example.org , i will try to resolve a problem.
Best regards, Gregor, Famatech Support Team