Port 80 Forwarding

Hi

We are having a new system bulit which uses part of our server as a web server. The person making the system requires that any HTTP traffic comes to our router is forwarded to the HTTP port on the server. I though i had set up the setting on the router correct but now it doesn't seem to work. On the router (Draytek Vigor 2820) i have setup the port forwarding from Public Port 80 to the IP address of our server to the Private port 80, where the developer has put a default.htm page.

Any suggestions would be most grateful

Kind Regards