Incoming NAT on Multi Wan setup Fails

[nzink]

Incoming NAT on Multi Wan setup Fails if client is coming from one of the  WAN subnets

Scenario (bogus IPs)
Wan1  :  Static IP   10.1.1.1 / 24
Wan2:  Static IP  172.16.1.1/24
Internal:  192.168.1.1
192.168.1.10   WWW server
192.168.1.15  www  server
LoadBalnacer1    Wan1 and Wan2  Failover only  outgoing only.

Port forward Nat.   10.1.1.11 -> 192.168.1.10     port 80
Port forward Nat.   172.16.1.1 -> 192.168.1.15  port 80

Version 1.2.2    
Outside Client.   10.1.1.100    can access  10.1.1.1   can ping 172.16.1.11 but cannot pull up web page on 172.16.1.1
Outside Client.   172.16.1.25    can access  172.16.1.1 can ping 10.1.1.100    but cannot pull up web page on 10.1.1.100    
Any other outside client  as long you are not on one of the networks  work as expected.
Can you tell me If this a setup issue?  Any ideas how to fix?
Thanks

[clarknova]

10.1.1.100 doesn't know where to find 172.16.1.1 unless

a)10.1.1.1 is its default gateway or
b)it has a static route designating 10.1.1.1 as the gateway to 172.16.1.1/(24-32)

If 10.1.1.100 can ping 172.16.1.1 then perhaps you have done one of the above?