Routing over ipsec

[prkon]

Hello,

since a week we have to route a network over an IPSec-tunnel
and it seems so, that we are not able to do so.

Our configuration:

Network1 172.20.10.x/24 with PFSense location 1:
    1 foreign router on 172.20.10.240
    1 static route: 10.18.10.138/32 over 172.20.10.240

Network2 172.20.20.x/24 with PFSense location 2:
    1 static route: 10.18.10.138/32 over 172.20.10.240

location 1 and location 2 are linked with an IPSec-tunnel.

both networks have correct connections net1 <-> net2.
from network1 we have access to 10.18.138/32.
from network2 we can ping the foreign router on 172.20.10.240.

Now we must have access to 10.18.10.138/32 from network2 over IPSec
and over the foreign router in network1.

layout:

http://www.gliffy.com/pubdoc/1257444/L.jpg

Can you help us?