OpenVPN site-to-site DNS problem

[mki]

Hi all

I've successfully configured a site-to-site OpenVPN with two pfSense Boxes (both 1.2.3), but I can't handle one problem.
Server domain: doma.in
Client domain: sub.doma.in

Ping works from both sites but I can only resolve DNS names from client site to server site.
On the OpenVPN client I've configured DNS forwarder as follows:

I've configured the OpenVPN Server the same (Domain: sub.doma.in, IP: address of the OpenVPN client) but it doesn't work.

Can anyone help me?

Thanks a lot in advance
mki