Accessing Load Balancer from internal IP

hi,

we're trying the load balancer for http (network security) and have the problem, that we can't access the load-balanced service from the internal lan.

the load balancer is listening on an external ip x.x.69.201 and available from everywhere (tried "automatic filter rule", but also explicit rule).
it has two internal servers as upstream (10.x.x.11, 10.x.x.12).
access from world - fine.
but i can't access x.x.69.201:80 from both hosts, and also not from other hosts in this 10.x.x subnet.

the 10.x.x subnet is masqueraded to the internet.

if i add a source nat rule to a host in the 10.x.x.x subnet i'm able to access the load balancer.
what i've seen load balancing is done with iptables, do i need additional rules?

thanks for your help

jodok