Dameware IP class problem

Hello;

I've using DameWare Remote Support v9 - DRS1.

I have two IP class first one is 172.16.10.xx, it's local PC's class.

Second IP class is 192.168.1.xx, it's for servers and shop's computers. "We have 10 shops".

When I want to connect shops' pc I must to use 192.168.1.xx IP class. "But Shop's computers have 172.16.1,2,3,4...10.xx ıp adress"

When I connect to local PC I must to use 172.16.10.xx IP class.

We have forinet 100D. It is firewall and DHCP server.

Some shops has fortinet 40C "I have not any problem because central firewall and shop's modem same fortinet"

Some shops have Zyxcel ADSL modem and their IP class 172.16.10.xx

Have you got any idea about this scenario.

Thanks.