Virtualmin Pro install failed on CentOS Linux 4;7 - File Not Found error

I'm attempting to install Virtualmin Pro using the command provided in the serials page.

I get the following fatal error

An HTTP error occurred:
URL: http://mirror.centos.org/centos/4/extras/i386//headers/header.info
Status Code: 404
Error Message: Not Found

Navigating to the mirror.centos.org site, I find that the centos/4/extras/i386//headers does not exist

What should I do?

Status: 
Closed (fixed)