VPN with transparent mode

[nvelocity]

We have an IPSEC VPN with a FGT100D on one end and a FWF60A in transparent mode behind a Cisco handling NAT on the other. I can bring up the tunnel and the firewalls can ping each other but the clients cannot. I have put a manual route on a windows PC directing traffic for the VPN to hit the Fortinet first. Should that route be on the Cisco? Because we' re doing transparent mode are there any tricks with NAT we need to consider? Help appreciated.