Nt Workstation 4.0 SP4

I am a remote user, I dial from home into my server at work. I connect to an ISP, after connecting succesfully, i then use a VPN connection to connect to my server. Once connected i try to join to a DOMAIN and i enter my domain name but it never finds my domain. How can i join my domain succesfully being connected remotely?. I am able to succesfully connect to my server but when i try to join the domain, it never finds the domain. HELP!!