Reach Terminal Server behind ISA Server 2000

Hi, I have a Windows 2003 Server with Terminal Services that is behind a ISA Server 2000, I can connect from any machine in the Domain, but I cannot connect from Internet, I’ve created a IP Packet Filter for port 3389, Server Publishing Rule and Protocol Definition but I cannot reach it yet.

Can anyone help me?

thanks in advance.
Josue Gamarro Quintana