Assigning IP Address in IIS

I’m trying to set up a new website in IIS, but it won’t allow me to “start” the site once I’ve done it.

This is a public IP address that was received from our ISP. I have assigned it to the server in the Network applet of the Control Panel. Then I created the site in IIS, assigned this IP address, and pointed the site to its default home directory. At this point, when I try to “start” the site, I get the following:

Winsock Error: Unable to assigned requested address.

Does anyone know what this means?