ISA Web Publishing

I'm having some trouble setting up another web server rule on my ISA 2004 server. I have one for my webmail pointing to exchange server and it works great for external users. I now need another web server published to point to my library server. I followed the same steps to make this but it doesn't seem to work.

steps i took

1 publish web server - name blackboard
2 allow
3 ip 10.13.63.20 - library server
path /webopac/main - path i need to access
4 public name library.mpl.herzing.edu - external users type this into browser to access the server
5 web listener is the same one as the webmail. webmail works fine. both on port 80 allowing all networks and local host , external
6 all user access

all settings in properties after i created the rule are the same as the working webmail link.
From my internal browser i can type in 10.13.63.20/webopac/main and get to the server. i cannot type in library.mpl.herzing.edu/webopac/main

not even trying external just yet

any help or guidence on this is greatly appreciated.