Change ip on UnixWare 2.1.2

I changed the IP whit Ifconfig and I used ping to test the conetions the conection is rigth on my LAN (NetA)

But, I have two networks for example:

NetA route to NetB and vicevers

On NetB ping to any machine on NetA, it is respons successfully. but I ping to UNIX server no respons.

I need to configure something more???

Thanks

Have the network people been notified? It might be blocked by a firewall, you may be conflicting with another IP, or your DNS server is pointing to the wrong (now non-existant) place...