Can't load balance TCP 53 port

[rasca]

Hi everybody,
I'm trying to load balance my DNS service via TCP and UDP, but I'm having problems with the first one.
Even I've got a firewall rule which allows both TCP and UDP on port 53 and even if I've configured a load balancer server pool with protocol dns, I'm just able to connect on my IP balanced address via UDP.

Obviously I've disabled DNS forwarder and obviously the two real servers are listening on both tcp and udp. From the pfsense console I'm able to netcat the 53 tcp port on the real servers, but an nmap on the IP balanced address make me see just the UDP port open.
I've tried also to add a new virtual server with just protocol tcp, without success.

Do you have any suggestion to help me resolve this problem?

Thanks a lot for your time,

Raoul Scarazzini
rasca@miamammausalinux.org