Proxy server behind PfSense Multiwan

[keitaro]

Hi, i installed a Pfsense to loadbalance 2 isps, but we alread have a proxy on the network.

ISP+ ISP –-->Pfsense----> Proxy/NAT(isa server) ----> LAN

My problem is. Since WAN2 is online... all traffic goes trough WAN2, and don´t load balance wan1/wan2 .... this is because the proxy behind pfSense? or some miss configuration?  (fail over works great)