RDC licensing across forests

I'm trying to setup a Remote Desktop server to get licensing information from another server in another forest. Both are Windows 2012R2 servers

1- Full tow way transitive trust is present and working between the forests/domains.

2- Licensing server is part of Terminal Server License Servers group in all domains.

3- RDS Host Servers is part of the Terminal Server Computers group on the RDS Licensing servers.

4- Domain admins or the Host servers are admins of the RDS Licensing server.

5- The following ports are open between both servers: UDP 137 UDP 138 TCP/135 TCP/139 TCP/445 TCP/49152-65535

I still have a “licence server …… Unavailable” error.

What I’m a missing?

Thanks.