Doubts on configuration, policy routing and multiple LAN

[hades2009]

I have a network in a school with 2 different networks between teachers and students, I set up pfsense with each other and in the pfsense wan an ISA server that will be my Internet exit and where will my firewall rules, I just want the pfsense to connect the 2 network segments above and then redirects all traffic from each LAN to the WAN with policy routing and that are not among them, the problem part when I want to spend some sort of traffic between the 2 networks LANs, Example:

from the subnet of LAN I make a request to a server on the OPT1, when the petition reaches the default pfsense execute that policy routing rule and send it to the wan, So far so good for me, the problem is when the isa server sends the packet to the opt1 that the pfsense wan then send the package back to the isa and so on until the customer gives a ttl time expires
The configuration of the isa is fine, it send the request to the wan correctly, is this that instead of passing the packet to OPT1 is making it back to isa

My rules
in the 2 LAN everything in and let everything out I apply the policy routing
In the WAN permit any to any

lan–---
          ------WAn----- Microsoft Isa Server
opt1-----